Lethargic/nonfunctional heat pump fan

I'm a young, very new homeowner with rather limited funds, so I'm inclined to attempt this repair myself to the extent that it is possible. I've called a couple of HVAC technicians, and they want anywhere from $200-$1200, which could deprive me of anything from my living room furniture to ALL of my furniture. You all seem well-informed and kind-hearted, so please, help me!

It'd been cool (below 70 at night) for about a week when I installed my new Nest thermostat (a housewarming gift), so I hadn't activated the A/C for some time. Upon completing installation, I noticed the air coming out of the vents was not cold. I quickly discovered that the fan on the external unit was not moving. I spent two hours on the phone with Nest technical support before hooking the old thermostat back up to find the behavior was consistent across the two. Something's awry with that heat pump.

I'll break it down:
- The air handler seems to be functioning fine
- The fan on the external unit does not move
- During a series of clicks (motor start attempts? not sure if it was the Nest doing this, a feature of the heat pump, or a phenomenon of some charge threshold being reached in the capacitor) at 1-2 second intervals, I did observe the fan move once, loosely, about half of a rotation
- I tried replacing the dual-run capacitor, even though the installed one was pretty immaculate in appearance. It didn't work.
- There were two wires connected to the common terminal on the capacitor. Didn't seem consistent with what I'd read during my research on capacitor replacement, so thought maybe that'd be meaningful.
- the pull-out fuse in the disconnect box (i'm sure that's not the proper terminology) and the disconnect box itself are original, i'm pretty sure. And the place was built in 74.
- There was a tiny, mild discoloration on the circuit board near a transistor, but I'm pretty sure it was nothing. I only mention it because the other wiring in the vicinity of the capacitor looks to be intact.
- It's an Amana heat pump. I'm not at home right now, I'll get the model number off of it if that's relevant to you guys, but it's a newer model. I think it was installed in 2010. Attached is a picture.

I unscrewed the fan motor and exterior housing, so that's why the fan is askew in the picture.

 

Welcome to the forums.

There isn't much you can do visually. You're going to need a voltmeter to find out where the A/C signal is getting lost.

 

Alright, I'll get one tomorrow afternoon. What should I do with it?

(and thanks)

 

Makes and model numbers are always helpful to us as we can look up the equipment and see what you are looking at as well as the wiring diagrams.

Do you have electric coils for re-heat ?
I'm guessing at this point the inside blower comes on when you demand it and the nest is showing active (has its 24v).

Look for where the wiring from the thermostat and the condensor meet at the air handler. Carefully remove access panel if needed. You may need to turn power off to air handler first to remove cover safely. You then need to set the stat to A/C. The blower should run and you should measure 24vac between the Y and C terminals. We'll start here.

 

So, I left the breaker for the air handler on yesterday, to keep air moving through the house. Left the disconnect box on 'off' so the heat pump wouldn't be affected. Noticed the fan wasn't running when I got home. Put the disconnect plug back in the 'on' direction, turned on both breakers - - thermostat won't even turn on.

...I got my hands on my friend's super-fancy multimeter, but I don't see a Y or C terminal to measure. Got a picture of the wiring diagram, got the model number from the heat pump. I feel like this system is crashing down around me, definitely should have sprung for the home warranty.

Just poked my head in the air handler and there is definitely something going on in there. There's a loose (one end is fixed, but the one end looks like it should be somewhere) black-sheathed copper wire that has turned completely blue with corrosion, and there's an object (don't know what it is) with four terminals in there, whose M2 terminal is covered in something that melted, then charred. There's a purple wire that was touching it whose sheathing was burned through; there's copper showing.

The likelihood that this is a quick, easy fix just went down, I suspect, but my motivation to do it myself goes up with the bill for a technician to repair it. I appreciate y'all's patience and assistance.

EDIT: Sorry, I don't know whether I have 'electric coils for reheat' or not. I do have aux/strip heat, but I'm only aware of it on a high level.

 

http://www.routeac.com/manuals/goodm...rts_manual.pdf

Looks like you need a heat sequencer in your air handler and some slip connectors.

There should be some numbers on the base of that sequencer (probably B1256559) to help you order a new one.

This does not explain the problem with the outdoor unit.

 

Awesome. The sequencer is on the way, I'll have it before this week's end. I was definitely hoping that this problem was closely related to my original issue, but am not surprised by your prognosis. I suppose when I receive it, I replace the faulty one, hook everything up as it was before, trim and attach the black wire to the terminal corresponding to the one that melted? Is this (melting heat sequencer) something that autonomously happens on occasion, was it caused by the heat pump fan issue, or did I probably do something to aggravate it?

Also, what type of wire connectors do i need, specifically? It looks like there are different ones for different gauge wires?

 

I see we have the manual for the heat kit but not for the actual air handler.

You'll probably need yellow size crimp terminals for your sequencer connections.

 

I would get Yellow slip on connectors. I call them female spade connectors.



Strip back the wire untill you see clean copper and it helps if you issue a profanity when squeezing down on your crimpers. The important step is grabbing the new connector in one hand and the wire in the other to see if the connector pulls off of the wire after you crimp it.

Thermostat battery terminals can corrode and become unreliable when batteries leak in them. A Q-tip and some rubbing alcohol might clean the battery oil from them.

 

PJ you type too fast for me.


Is that an ARUF air handler?

 

And after that..... if there's a little corrosion left.... a pencil eraser works well.

 

@Houston: yes, it's an ARUF unit. I don't know what that means, but I see a serial on the air handler beginning with ARUF.

So I've replaced the heat sequencer...

...and symptoms presented are back to what they were when I opened the thread. I don't see Y and C terminals anywhere but in the thermostat wiring, so I stuck my brand new multimeter leads in there and read 3.4... units. It's a point of pride of Nest, seemingly, that the C wire is not needed, so it's not connected. I'm not sure if I'm using the multimeter wrong, or what.

Occurence of interest: Apparently removing the plug from the disconnect box outside does nothing and the heat pump continues to receive power. Discovered that the top switch in this random secondary breaker box near the air handler cuts off power to the air handler blower and the heat pump, as far as I can tell. No idea what the bottom one does. Also, the breaker labeled A/C in the main box seems to do nothing at all.



Please advise.

 

Check the low voltage connections in your outdoor unit.

Highlighted blue...

 

Sorry, I'd appreciate if you'd ELI5. I'm having a hard time making out the lettering on the diagram, but I can do colors. The connections look OK, I presume you want me to take a measurement somewhere with my multimeter? I should set it to 200 AC volts and test C to each other wire?

 

Yes measure C to Y, R, and O.
Should read 24 volts AC each time.

 

And so it does. It was clicking incessantly while I took the readings, like power was coming on and off. Every 20 or so clicks, the fan seems to try to move. Also, that low-resolution wiring diagram you produced was printed on the interior of the panel covering those connections. Right on. If anybody wants a higher resolution version I'll take a picture when it's bright out.

...this is gonna be pricey, isn't it?

Thanks again for all your help

 

In case that wasn't clear, I'm getting 24V ±0.1V between C and each of Y/R/O.

 

Check for voltage across the high pressure switch and low pressure switch.

 

Sorry, I'm not sure how to do that. I can do that from the main circuit board on the heat pump(pictured), or is it inside the body of the unit somewhere?



I see the components of the diagram you're referencing, but I don't see the physical correspondents.

My friend's dad, who's a auto hobbyist, has pressure gauges, a vacuum pump, and a leak sensor if we need any of that.

 

The 2 Yellow/pink wires are the low pressure switch and the 2 blue pink are the high pressure switch. I'd pull each out of the board a little and measure across them.

 

Only one blue/pink wire, boss. No voltage measured between high-pressure wires. Sticking the lead into the back of a 'crimp connector' on visible metal (the crimping part) should give a proper reading, right? Space is tight in there.

 

Place one lead on 24 volt common (C) and place the other lead on each of the 3 leads on the board.
The other low pressure switch wire is the wire nut connection between thermostat Y (often a yellow wire) and the unit Blue/Pink.

 

High pressure switch voltage jumps to 24 then returns to around 2.. both low pressure circuits read 24v.

The only blue/pink wire is attached to the y connector on the board..

 

If you are reading across the pressure switch 24 volts = a tripped pressure switch.
If you are reading between 24 volt common (C) and Y, and each of the pressure terminals 24 volts the pressure switches are not tripped.

 

pink/yellow 1 to pink/yellow 2 : 0V
pink/yellow 1 to C : 24V
pink/yellow 2 to C : 24V
blue/pink (Y) to C : 2-24V (jumps to 24, falls back to 2, jumps back up to 24, usw synchronized with loud clicks

 

So it is a hi pressure switch tripping or the 24 volt signal to your heat pump.

Is the condenser fan motor running?

Can you measure from the remaining blue/pink wire to com?
It is an orange wire nut connection between the control wire from the house and your heat pump.

Post more pics from further back if you cannot find it.

 

So my main problem is still that the condenser fan isn't running. The only signs of life are the clicking noises that we now know coincide with the switch tripping over and over again. I don't see an orange wire nut or anything labelled 'com'.. Here's what I'm looking at.

 

Okay, it is a blue wire nut connection.
Check the blue wire with a pink stripe to your 24 volt common (C or 24 volt com , blue wire).

 

That's the circuit whose voltage is jumping up and down. You want me to measure it from the wire nut instead of from the terminal? I don't imagine the reading would be different.

(i'm in the software industry, "com" to me pangs of "com port", not "common", my oversight)

 

Is the compressor running without the outdoor fan?
If this is the case we should have a constant 24 volt signal at the wire nut but not at the control board.


You have a pressure switch between the wire nut connection and that wire at the control board.
You can click the second diagram that I posted and get a bigger picture that let's you select a plus sign to see the original image. You can clearly see the pressure switch when you see the original image.

We need to determine if the pressure switch is dropping the signal or are we not getting a constant 24 volt signal to the outdoor unit.

 

OK - so I thought for a minute I'd gone crazy, because the blue/pink wire was reading a solid 24V, and the orange wire was the one fluctuating. Then something went SHTUNK(sic), that relay at the bottom of the panel or something behind it flashed some sparks, and the blue/pink wire went back to fluctuating. I'm finding that the voltage across the orange wire is fluctuating in the same pattern as the blue/pink one now. And, the voltage is fluctuating in parallel in 2 wire nuts with blue/pink and orange wires emerging from them.

Re: is the compressor running? Nothing outside of the air handler is running, as far as I can tell. The compressor would be making noise if it was running, right?

 

I'd isolate the control wires at those blue wire nuts and measure again.
If the signal is constant after you isolate, I would unplug the reversing valve and get an ohm reading across the solenoid coil of the reversing valve.

 

I'll see if I can't get up early and do this before I head off to work. When you say "isolate", do you mean unscrew the wire nut and test the loose wires individually against control? If I need to disconnect them and test, which ones should I?

OK, now I know what a reversing valve is. It'd been described to me but not named. I presume that's located in the panel below the panel I've opened containing the circuitboard. When you say 'unplug', you mean disconnect both wires from the two lone terminals and test between for resistance. What do I set my multimeter to? Ranges by powers of ten between 200 and 2 million.

But I only want to do that if the signal is constant, right?

 

I believe that you posted erratic 24 volt signals between Y and C and between O and C. We should isolate at your blue wire nuts and test these points.

If C touches Y or O it will pop the fuse or cook the transformer.
If Y or O touches the body of your heat pump it will pop the fuse or cook the transformer.
Be Careful.

 

I'll be cautious. I've got some clamps somewhere, that should guarantee they don't touch anything they shouldn't. To be clear, though, I'm unscrewing those two wire nuts with orange and blue/pink wires in them, separating the wires, and testing whichever wire is live against common in both?

FWIW the fan still moves occasionally, like a quarter turn.

 

Sorry, I'm not comfortable enough with what you mean by 'isolate' to proceed.. There appears to be several different definitions.

If you were trying to scare me away by threatening my transformer, you're underestimating how broke I am :[

 

I just meant take off the wire nuts and separate the wires. Measure the Y wire to the C wire and measure the O wire to the C wire from the house.

Before that I would remove the wire nuts but leave the wires connected. If you get a constant reading between Y and C and between O and C it points to a high pressure switch tripping. If you get erratic readings, separate the wires and retest to prove that your contactor coil, reversing valve coil or a wire to these items isn't causing the erratic reading.

Amazon.com: Jard Magnetics 4031FK 40va,120/208/240 Primary VAC, 24 Secondary VAC Transformer: Home Improvement

A transformer is 24 bucks at Amazon. A low voltage fuse is a couple of dollars at an auto parts store. I am only trying to spare you the delay of getting either one by letting you know that you can't touch the wires to anything but your meter leads without possible damage. I'm confident that you can test this without shorting anything to ground.

 

OK, after removing the wire caps, both signals were fluctuating still. I wouldn't call it 'erratic', as the voltage hops up and down with the sound of a circuit breaking somewhere inside the unit. The fluctuation and clicking sound stopped when I separated either pair of wires, and I was able to measure 24-26V during that time from the corresponding wire coming from the house.

2 observations:
1) there are two different switches/breakers being triggered here. The most common is one inside the unit that I can't see. Every so often, the main one just under the circuit board pops. I think that might be the thermostat realizing its attempts are futile, and cutting the cooling signal, perhaps to allow the capacitor to charge or something like that.
2) there's a loose wire among these wire caps. Wouldn't it be nice if all this was just because of a loose wire? Pictured below along with the two wire caps isolated and tested.

 

I would disconnect R, Y , C and O and measure Y to C and Y to O on the wires coming into the heat pump from the house. If it still cycles oddly it prove that the problem is not outside.

I really would have guessed a pressure switch is tripping.