Carrier TECH 2000 not starting

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  #1  
Old 07-25-10, 07:29 AM
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Carrier TECH 2000 not starting

I have a Carrier TECH 2000 model 38TR030300 air conditioner that quits working last night. It was working on an off for a couple of weeks now and until last night, it never starts up again.



In picture above, I found that I use a stick to push that little thing (not what it calls) to go in then the air condition works fine. So, my question is, do I just replace that whole thing? Or, is there some other problem that causes this thing to not pushed in and locked it there until the air inside the house reaches the temperature set on the thermostat? It's going to be very hot day today. Any suggestion/help is much appreciated.
 
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  #2  
Old 07-25-10, 01:35 PM
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the contactor isnt pulled in huh, well the thermostat sends 24 volts to the contactor to pull it in. but the 24 volts can go to a safety switch before going outside so i say check that your condensate pump, little box on floor next to furnace to see if its filled with water. if you have a condensate pump. you can also check to see if your getting 24 volts to the sides of the contactor, not the big wires, and if you are then the contactor needs replacing.
 
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Old 07-26-10, 07:44 AM
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Thanks for the response. I'm not sure what the "condensate pump" looks like but I do have a water drippings hose. My brother-in-law did check the thermostat cable and it does have electricity coming in. I'm not sure if it's 24volts or not. I was looking for a contactor replacement and the local store here charges $40 for total cost. Any place where I can find one? What could happen to the contactor to cause it to not pull in anymore?
 
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Old 07-26-10, 03:22 PM
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The contactor uses a 24v coil to create a magnet that pulls the contactor in. Then the contactor passes 240v through it. Before you replace the contactor, verify that there is in fact 24v on either side of it (not at the line voltage side, but blk/brwn to purple). Replacing the contactor will do you no good if you aren't getting 24v at the contactor coil because the next one will do the same thing.
 
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Old 07-28-10, 05:57 AM
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Question

Originally Posted by Jones1 View Post
The contactor uses a 24v coil to create a magnet that pulls the contactor in. Then the contactor passes 240v through it. Before you replace the contactor, verify that there is in fact 24v on either side of it (not at the line voltage side, but blk/brwn to purple). Replacing the contactor will do you no good if you aren't getting 24v at the contactor coil because the next one will do the same thing.
I replaced the contactor and it was working for about 10 hours or so and then after midnight last night, it stopped again.

The wires from the thermostat are red and white. The red wire connects to the blue wire that goes to the compressor and then a black wire comes out of there to connect the contactor. The white wire connects to the brown cable that goes directly to the contactor. I measured the red and white wires and it is about 25v. Suppose I measure either side of the contactor and it's not 24v, what do I do then? Or, what does that mean?
 
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Old 07-28-10, 08:18 AM
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One more thing, if I measure both ends of the contactor and it still says 24v, what then? What could the problem be? How steps do I proceed next?
 
  #7  
Old 07-29-10, 07:17 PM
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I would disconnect and check the thermostat leads themselves; if voltage is there but they don't pull in the contactor when you hook them back up I'd check for an open circuit between blue and black; it could be a pressure switch or I think some compressors use low voltage crankcase heaters; a high pressure switch seems more likely since you got it working again once.

Something that would help us to know is which parts of the AC system aren't working; does the inside blower work? The voltage that operates the condenser outside comes from the air handler or furnace inside, so no power to one == no power to the other. Was it cooling before it stopped working? Finally, how does the condenser look? Is it dirty, matted up, overgrown with weeds? If it is, clear it of vegetation and hose it down, being careful not do drive dirt directly into the fins (aim downward).
 
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Old 07-30-10, 07:02 AM
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Originally Posted by Jones1 View Post
Something that would help us to know is which parts of the AC system aren't working; does the inside blower work? The voltage that operates the condenser outside comes from the air handler or furnace inside, so no power to one == no power to the other. Was it cooling before it stopped working? Finally, how does the condenser look? Is it dirty, matted up, overgrown with weeds? If it is, clear it of vegetation and hose it down, being careful not do drive dirt directly into the fins (aim downward).
I'm not sure exactly which part is not working. Everything works fine. The air is cool when it works and it wasn't too dirty. The biggest issue seems to be the contactor is not pulled in despite a brand new contactor. But why was it not pull in when every where I measured says 26v, that's the main problem. Below is the diagram of what I've tested. The green lines and circle is where I tested the voltage. They are all 26v. The red, white, blue, yellow, black and purple are the wire cables.



Yesterday morning I was measuring the voltage, poking around, and disconnecting and reconnecting the wires again and suddenly it worked for another 12 hours or so. I'm pretty sure if I'm start poking and disconnecting/reconnecting the brown, black and purple wires it will work again.

Okay, so where do I go next from here since all wires measured 26v and it's a new contactor?

Here's another question. The original contactor (as shown in the picture of my original post) the black and brown wires are on the left and purple is on the right. With my new contactor, it's up and down. Do I put my black and brown wires on the top and the purple wire on the bottom? Does it matter?
 
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Old 07-30-10, 10:07 AM
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If you have 26 volts at the contactor and it's not pulled in it's either a weak 24 volt transformer which is located in the air handler/furnace or a weak/corroded connection in the wiring between the transformer and the contactor. Also make sure the contactor is rated for 24 volts for the control voltage coil. Some commercial contactors are made for 120 volt control voltage instead of 24.
 
  #10  
Old 07-30-10, 10:21 AM
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Originally Posted by jeggs View Post
If you have 26 volts at the contactor and it's not pulled in it's either a weak 24 volt transformer which is located in the air handler/furnace or a weak/corroded connection in the wiring between the transformer and the contactor. Also make sure the contactor is rated for 24 volts for the control voltage coil. Some commercial contactors are made for 120 volt control voltage instead of 24.
What is the transformer looked like? Is there a way to test if the transformer is weak?
 
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Old 07-30-10, 11:04 AM
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Originally Posted by Charlie2 View Post
What is the transformer looked like? Is there a way to test if the transformer is weak?
Here is a link to a universal replacement transformer. Yours may have spade terminals instead of wires. You have to make sure the replacement will match your input voltage (120, 208 or 240 volts). Some have taps for all three. Some don't. Get one rated for at least 40VA output and is desinged for HVAC. There really isn't an easy way to test the old one without knowing the ohm ratings of the coils in the transformer when it was new. 120/208/240 Volt, 24 Volt Output Transformer, 40 VA Rating (Universal Replacement for many brands): American HVAC Parts
 
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Old 07-30-10, 11:11 AM
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Originally Posted by jeggs View Post
Here is a link to a universal replacement transformer. Yours may have spade terminals instead of wires. You have to make sure the replacement will match your input voltage (120, 208 or 240 volts). Some have taps for all three. Some don't. Get one rated for at least 40VA output and is desinged for HVAC. There really isn't an easy way to test the old one without knowing the ohm ratings of the coils in the transformer when it was new. 120/208/240 Volt, 24 Volt Output Transformer, 40 VA Rating (Universal Replacement for many brands): American HVAC Parts
Thanks, Jeggs! So, the one you linked here is 40VA rating and is for HVAC, correct?

Where on the furnace or air handler do I look for this transformer?
 
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Old 07-30-10, 11:19 AM
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Another quick question. The two wires (red and white) that came out of the house to be connected to the brown and blue wire inside of the AC unit is from the transformer inside the house, correct? If yes, why then is the transformer weak when I measured and it reads 26v as it should be?
 
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Old 07-30-10, 11:24 AM
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Originally Posted by Charlie2 View Post
Thanks, Jeggs! So, the one you linked here is 40VA rating and is for HVAC, correct?

Where on the furnace or air handler do I look for this transformer?
The one in the link is a universal one for HVAC, is 40VA, and will work on various input voltages. The transformer is in the air handler possibly in a separate box with a removable panel with the fan relay, sequencers, and various wiring. You may be able to find one locally at a cheaper price. Make sure you write down where the wires go and take the old one with you. PLEASE MAKE SURE the 240 volt circuit breaker to the air handler is off before you go digging around in there.
 
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Old 07-30-10, 11:30 AM
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So, it's inside the metal where the air blows to the rest of the building, correct? That means I have to open up the metal panel to find it, right?
 
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Old 07-30-10, 11:32 AM
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Originally Posted by Charlie2 View Post
Another quick question. The two wires (red and white) that came out of the house to be connected to the brown and blue wire inside of the AC unit is from the transformer inside the house, correct? If yes, why then is the transformer weak when I measured and it reads 26v as it should be?
If the transformer is weak it can still put out 24 volts but does not have enough amperage to pull the contactor in. As I stated in an earlier post make sure the new contactor is rated for 24 volts. If you have one for 120 volts control voltage instead of 24 it will act like the transformer is weak. The volt rating for the coil on the contactor should be printed on it somewhere.
 
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Old 07-30-10, 11:37 AM
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Originally Posted by Charlie2 View Post
So, it's inside the metal where the air blows to the rest of the building, correct? That means I have to open up the metal panel to find it, right?
Right. There will be an access panel on the unit to get to the blower, coil, and electronic devices. It might be best to call an HVAC tech if your not familiar with the location and wiring of 240 volt circuits in the air handler.
 
  #18  
Old 07-30-10, 11:45 AM
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I'm pretty sure the contact is rated 24v. I went into the supplier with the Carrier model and serial number to order the part.

Okay, so even if the transformer can output 24v, you're saying maybe it's not enough amperage to pull the contactor in. So, is there a way to measure the amperage with a multimeter?
 
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Old 07-30-10, 12:01 PM
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Originally Posted by Charlie2 View Post
I'm pretty sure the contact is rated 24v. I went into the supplier with the Carrier model and serial number to order the part.

Okay, so even if the transformer can output 24v, you're saying maybe it's not enough amperage to pull the contactor in. So, is there a way to measure the amperage with a multimeter?
You can measure the amp draw between the transformer and the contactor if your multimeter has an amp function. It should be .75 to 1 amp. If it's lower the transformer is bad. If it's .75 to 1 amp the contactor should be pulled in. When a transformer goes bad it will often work until it heats up and then the amp output will drop. You said your system worked for a while and then quit and when it's off for a while it will work again. That leads me to believe it's a bad transformer or corroded wire somewhere not having good contact if you have 24 volts at the contactor but it wont pull in.
 
  #20  
Old 07-30-10, 12:20 PM
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Originally Posted by jeggs View Post
You can measure the amp draw between the transformer and the contactor if your multimeter has an amp function. It should be .75 to 1 amp. If it's lower the transformer is bad. If it's .75 to 1 amp the contactor should be pulled in. When a transformer goes bad it will often work until it heats up and then the amp output will drop. You said your system worked for a while and then quit and when it's off for a while it will work again. That leads me to believe it's a bad transformer or corroded wire somewhere not having good contact if you have 24 volts at the contactor but it wont pull in.
Okay, so I put my red lead on the read wire and black lead on the white wire and measure the amp, correct? If the it is lower than .75 then it's bad but if it's above .75 then it's good, right? So, what if it's .75? Where do I from there trouble-shooting?
 
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Old 07-30-10, 12:27 PM
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Originally Posted by Charlie2 View Post
Okay, so I put my red lead on the read wire and black lead on the white wire and measure the amp, correct? If the it is lower than .75 then it's bad but if it's above .75 then it's good, right? So, what if it's .75? Where do I from there trouble-shooting?
.75 should pull in the contactor. If the amperage goes down as the transformer heats up , it's a bad transformer.
 
  #22  
Old 07-30-10, 12:30 PM
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Measuring the amp on the red and white wire should tell me what amp it is, right?
 
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Old 07-30-10, 12:38 PM
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Originally Posted by Charlie2 View Post
Measuring the amp on the red and white wire should tell me what amp it is, right?
Pull the purple wire off at the contactor labeled "C" and measure between the purple wire and the terminal the purple wire was on. Also check for 24 volts on the purple and brown wires at the contactor. Voltmeter must be set to measure AC voltage not DC.
 
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Old 07-30-10, 12:57 PM
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Originally Posted by jeggs View Post
Pull the purple wire off at the contactor labeled "C" and measure between the purple wire and the terminal the purple wire was on. Also check for 24 volts on the purple and brown wires at the contactor. Voltmeter must be set to measure AC voltage not DC.
Jeggs, thank you so much for your quick response. I'm very grateful for your help. I'll test the purple wire for amp as you've suggested.

Another question in this long thread that no one has addressed it is this:

The original contactor (as shown in the picture of my original post) the black and brown wires are on the left and purple is on the right. With my new contactor, it's up and down. Do I put my black and brown wires on the top and the purple wire on the bottom? Does it matter?

The old contact has the letter "C" for the purple wire but the new one does not seem to have it. Where do I connect the purple wire to?
 
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Old 07-30-10, 01:00 PM
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Originally Posted by Charlie2 View Post
Jeggs, thank you so much for your quick response. I'm very grateful for your help. I'll test the purple wire for amp as you've suggested.

Another question in this long thread that no one has addressed it is this:

The original contactor (as shown in the picture of my original post) the black and brown wires are on the left and purple is on the right. With my new contactor, it's up and down. Do I put my black and brown wires on the top and the purple wire on the bottom? Does it matter?

The old contact has the letter "C" for the purple wire but the new one does not seem to have it. Where do I connect the purple wire to?
Can you post a picture of the new contactor?
 
  #26  
Old 07-30-10, 01:05 PM
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I have the Gardner Bender GDT-3200 multimeter. Can this multimeter be used to measure amp?
 
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Old 07-30-10, 01:09 PM
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Originally Posted by Charlie2 View Post
I have the Gardner Bender GDT-3200 multimeter. Can this multimeter be used to measure amp?
No. It will not measure amps.
 
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Old 07-30-10, 01:10 PM
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Originally Posted by jeggs View Post
Can you post a picture of the new contactor?
It looks very similar to this one?



Right now the purple wire is on top and the black and brown is on the bottom.

If there is no marking on the contactor, is there a way to test with a multimeter to determine if it is rated for 24v?
 
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Old 07-30-10, 01:16 PM
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Originally Posted by jeggs View Post
No. It will not measure amps.
Okay, I'll look for one that measure's amp tonight.

It's raining so I won't be able to take picture of the new contactor tonight nor work on it but I'll do that tomorrow morning if it's not raining.

Again, thank you so much!
 
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Old 07-30-10, 01:23 PM
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Originally Posted by Charlie2 View Post
It looks very similar to this one?



Right now the purple wire is on top and the black and brown is on the bottom.

If there is no marking on the contactor, is there a way to test with a multimeter to determine if it is rated for 24v?
That is the correct wiring. Set your meter to measure AC voltage and make sure you have 24 volts between the purple and brown wire when the thermostat is calling for cool but the contactor is not pulled in. Be careful of the 240 volt wires on the contactor. The ratings for the contactor should be printed on it. Maybe on the bottom. If not then they will be on the box it came in.
 
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Old 07-30-10, 01:28 PM
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Originally Posted by jeggs View Post
That is the correct wiring. Set your meter to measure AC voltage and make sure you have 24 volts between the purple and brown wire when the thermostat is calling for cool but the contactor is not pulled in. Be careful of the 240 volt wires on the contactor.
As shown in this diagram, the brown and purple wire does have 26v.



My next step is to measure the amp. I'll let you know what the amp is once I measure it tonight or tomorrow.
 
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Old 07-30-10, 01:31 PM
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You could probably buy a new transformer for what a new meter will cost.
 
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Old 07-30-10, 02:42 PM
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When you use a amp-meter. make sure you know how to use it. it is different from Volt meter. they must be connected in series. I suggest you get a clamp type amp-meter which is much easier to use. you won't even have to touch the wires.
 
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Old 08-01-10, 03:32 PM
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Okay, here's how I wired the new contactor.



Let me know if it's incorrect. And, will someone tell me what is this thing called and do?



Could this be the problem? On a closer look, I saw this on the bottom right corner. Does this look normal?



I have checked the transformer and I believed this transformer is part of the furnace, correct? If so, it's quite new. I just got a brand Train furnace about two years ago.

My next thing is to measure the amperage. I just got a new multimeter that can measure amperage but I am still trying to find information on how to measure amperage on these wires from the thermostat.
 
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Old 08-01-10, 03:52 PM
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Originally Posted by clocert View Post
When you use a amp-meter. make sure you know how to use it. it is different from Volt meter. they must be connected in series. I suggest you get a clamp type amp-meter which is much easier to use. you won't even have to touch the wires.
I got the alligator clamp but I'm not sure what you mean by "connected in series". I found this "how-to" but I'm not so sure about this last step.

Break into the circuit to measure its current. Set the red probe on 1 open end and the black probe on the other. This may require cutting a wire to get the probes in between the circulating current. The idea is to let the current flow through the digital multimeter to allow it to get a reading.
So, does it mean the following? I clamp the red alligator lead to the brown wire and the black alligator lead to the purple wire then turn on the thermostat, correct?
 
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Old 08-01-10, 06:09 PM
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Okay, I think I just a good video on how to measure amperage (current) on youtube.

Okay, so back to my case, I can either clamp the purple or brown wire to the positive alligator lead and clamp the negative alligator to the contactor and this will measure the amperage, correct?
 
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Old 08-01-10, 08:11 PM
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The how-to and the Youtube are both using the regular multimeter, they connect the wires in series (let the current go through the meter), not parallel. By using this type of meter, you have to mess around (cut in the circuit) with the wires. those are 120v and 240V, be careful. What I suggested is a different type of meter (a meter with a clamp/jaw on the top) which is much easier to use (you don't have to play with the wires). Google 'clamp ammeter', you will see them. If you want to use the regular multimeter, make sure you know how to connect those wires in series circuit, if you don't connect them right, you will get a big spark, and it will damage your meter.
 

Last edited by clocert; 08-01-10 at 08:30 PM.
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Old 08-01-10, 11:27 PM
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Originally Posted by Charlie2 View Post
Okay, here's how I wired the new contactor.



Let me know if it's incorrect. And, will someone tell me what is this thing called and do?



Could this be the problem? On a closer look, I saw this on the bottom right corner. Does this look normal?
That appears to be a time delay to prevent the compressor from short cycling.
 
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Old 08-02-10, 05:43 AM
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Originally Posted by clocert View Post
The how-to and the Youtube are both using the regular multimeter, they connect the wires in series (let the current go through the meter), not parallel. By using this type of meter, you have to mess around (cut in the circuit) with the wires. those are 120v and 240V, be careful. What I suggested is a different type of meter (a meter with a clamp/jaw on the top) which is much easier to use (you don't have to play with the wires). Google 'clamp ammeter', you will see them. If you want to use the regular multimeter, make sure you know how to connect those wires in series circuit, if you don't connect them right, you will get a big spark, and it will damage your meter.
The two wires (red and white) from the thermostat is only 26v not 120v or 240v. I already measured those two wires. I just don't know how much amp it has.
 
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Old 08-02-10, 07:58 AM
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I did not read all of your posts, only commented on amp measurement. If you only want to measure amp on 24V wires, then stay away from the contactor which has 120v and 240v. Disconnect one of the transformer wire (white, in your case) from the transformer, connect it to one of your meter lead. the other meter lead connects to the transformer post which the white wire was connected (that Youtube video shows you how to do this). set the correct amp range on your meter, turn the T-stat on, you will see the amp. (If you have a clamp ammeter, simply clamp around one of the transformer wires, don't even touch it, and you see the amp, no need to disconnect or re-connect the wires.)
 
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