Heat pump-cold works-heat shuts off


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Old 02-07-08, 10:15 AM
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Heat pump-cold works-heat shuts off

I have an Aire-Flo AFHEAT12B48 heat pump installed 9 mos ago. Cold worked great all summer and heat worked ok until recently.

Heres what I have found so far:
Handler fan runs continuous in heat mode
compressor shuts off after 10 secs(vapor line starts to heat up)
low pressure switch was cutting off compressor
checked pressures and low and high side are both about 125!!
switched to cold mode and low =45, high=150, blowing cold

Do I have a clog in the system?? Why else would my pressures be equal in heat mode (or is this normal). Why would it work in cold mode then. I bypassed the pressure switch and the pressures stayed the same but the drier started icing up (never went to defrost mode). Its cold, what can I do?
 
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Old 02-07-08, 10:26 AM
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Heat Pump Help

We are not supposed to give any sealed system advice sorry
but you need a tech anyway it sounds like you have a reversing valve problem if the unit is indeed not running if your guages are on the lineset you should get similar pressures if it is in heat if you want the suction pressure you have to put your low side guage on a tap above the lineset marked l or low. The fan running all the time could be a miswiring or if the unit is not heating it may not be satisfying to shut off
 
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Old 02-07-08, 11:10 AM
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The blower fan is working correctly. It will shut off by itself if it reaches setpoint. Its just with the heat not working it continues to run.

I don't think its a reversing valve problem - I can manually activate it and hear the pressures equalizing. It could be a control board problem that is not activating the reversing valve though. Its a $300 dollar board and a 2 day wait so I would like to verify it first before I replace it myself.

Can you give me advice on what you think the problem is? I would like a second opinion on this problem if I call a tech out. Just so he doesn't say I need a whole new system when the problem is just something minor.
 
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Old 02-07-08, 02:12 PM
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More testing complete

Ran a cooling only mode test - Brrrr.

Outdoor ambient temp 60 F
Indoor 66 F
Ran in cooling mode for 10 mins and:
Air from vents 43 F
Low press side - 52 psi temp - 38 F
High press side - 142 psi temp 55 F

All temps were taken with an IR gun. High and low temps were taken off the back of the condenser where gauges hook up to.

The only chart I have found for this does not go this low. But with the readings that I am getting it seems the cooling portion is at least working ok. I mean I am getting a 23 F drop in cooling mode. Should I be getting more?

Next I will try it in heat mode again.
 
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Old 02-07-08, 02:33 PM
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Wink

[QUOTE] It could be a control board problem that is not activating the reversing valve [Quote]
I think you will find that the stat is what controls the valve.
You know if you are not EPA this can cost you $10K?? Playing around with the freon. 9 months old where is the guy that put it in???? It should be under warranty
 
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Old 02-07-08, 03:56 PM
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Certified to Purchase and recover all types of freon

I am certified, but 95% of my experience is on automotive systems. My dad(also certified) does mostly industrial and commercial is the one who charged it but he lives out of state and working in another state right now so there is no warranty. Neither of our strong suits are residential systems. We did however get it installed and working until now.
 
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Old 02-07-08, 04:06 PM
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Heat test

Started to run heat test. Had to manually actuate the reversing valve to equalize pressures otherwise heat will never kick on. Swapped gauges over to read heating pressures. Started unit.

Ran for 10 secs until low pressure switch cutoff compressor. Same problem as before. Bypassed low press switch and let run. Indoor temp still 65 F, outdoor still 60 F. Low side pressure was 150 psi with 64 F temp. High side was 175 psi with 56 F temp.

Let system continue running. Temp climbed to 71 F max (was starting to heat the house) but compressor temp was getting close to 200 F. Shut system down when compressor started having a tough time (change in sound).

Looks like it is going to be another cold night tonight!
 
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Old 02-07-08, 04:09 PM
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Why else would my pressures be equal in heat mode (or is this normal).
Is outside TXV working????
 
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Old 02-07-08, 04:30 PM
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Funny you should mention that!

If a TXV is a thermal expansion valve then you and I might be on the same track. I pulled the condenser fan to get a better look and noticed a mark where the copper line to the 'thermal bulb' had been rubbing on the reversing valve. The bulb connects to what I would call an 'expansion valve' using automotive terms.

Anyway, the copper line definitely has a flat spot on it that may be blocking flow to the valve. Could this be the cause of my problems? Do the symptoms match?

I know on a car if the expansion valve is clogged you will get high high side pressures and low low side pressures. Would this account for my high and low side being close in heat mode?
 
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Old 02-07-08, 05:15 PM
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Bingo

That flat spot is a hole in the cap tube.

Call a tech, give model number of unit and have outdoor txv replaced.

No charge in the bulb mean the valve is closed and this is the cause of an open LP switch in heat.
 
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Old 02-07-08, 05:28 PM
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This is what I'm talking about.

http://img147.imageshack.us/img147/3...tuff018aq5.jpg
http://img225.imageshack.us/img225/7...tuff019dj9.jpg
http://img225.imageshack.us/img225/9...tuff020wm9.jpg

I guess this is the smoking gun!

You can't really see the flat spot from the pic unless you zoom in on it. To the left you can see the mark where it rubbed on the reverse valve. The last pic is how I had the gauges hooked to test in heat mode.
 
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Old 02-08-08, 12:39 PM
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Charge only port??

I hooked the low side of my gauges(still in heat mode) up to the third port on my system(the one in the center on top of the other two).

http://img225.imageshack.us/img225/9...tuff020wm9.jpg

(I thought it was a charge only port) When I did that my low side readings in heat mode seemed more believable. When the compressor kicked on I watched it drop until it hit 45 psi when the compressor shut off. The low pressure switch must be set at 45 psi then.

Looks like I just need a slight charge to get the system working again. My dad didn't think we got a full charge when the system was installed at the start of summer(tank ran out) but it worked pretty good until the temps here dropped below freezing at night(yes, it can get below freezing in Phoenix at night!)

At this time I think the capillary tube is not 'fully' blocked and still functioning(probably slower than normal). I am looking into getting the system charged enough so that it won't hit a low enough pressure to shut the compressor off in heat mode.

I still want to do some more research on the TXV in heat mode and see if it malfunctions if it will give the same symptoms as a low charge. If that is true then adding more freon to the system may or may not totally fix the system.

I will keep posting with my progress.
 
 

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