A/C Heat Pump Not Cooling

[JoelP]

Wouldn't you know it? When it went over 100F in Moab, Utah today our basement Heat Pump A/C has stopped cooling.  I have checked the breaker and it is still untripped.  I turned this off and back on to no avail. I set the AC to about 70F and the thermostat is still is reading a room temperature of  95F after some time.  Just yesterday my DW was complaining that it was cooling too much. 

I see that the circuit is drawing 13A on L1 ( 0A on L2).  Is this normal that the heat pump only draws from one 120V line?  When I crawled under I could hear some low level humming in the unit, but I see no large fan spinning and it isn't creating much sound at all. Also, I just changed the return air filter for the system this past week.

The vent fan is sending some air through the ducts, but that is not really A/C.  Any help would be appreciated.  What am I missing here?

 

[Alfa38User]

Make and model of the unit?? But since you have an Itasca listed, you likely have a basement model Coleman Mach unit. At those temperatures, the second compressor should have kicked in. Are you on a 30 amp lot by any chance?? At 13A only one compressor is running and cooling will be very limited. This unit usually has one 1 compressor on each leg, L1 and L2, on a 50 amp RV, so 0A on L2 is the reason. But at this point I cannot help further other than to suggest that you take a peek at the control board, it has LED indicator lights on it which may give you a clue.

(I have the same problem on my unit that I will likely address next winter, no troubleshooting done yet so the best I can provide is general information right now other than to suggest that the relay on L2 (second compressor) (found next to the control board) may have failed, not an uncommon problem!!. You might try the Winnebago board for more informed answers or call Colemen Mach. They were very helpful to me last time I called.)

You could always change the DW for one that doesn't complain as much, that might help for now. ;D Heh heh

 

[Old_Crow]

You could always change the DW for one that doesn't complain as much, that might help for now. ;D Heh heh

Probably be cheaper to just break down and buy a whole new RV, or at least a new heat pump. 

 

[JoelP]

Make and model of the unit?? But since you have an Itasca listed, you likely have a basement model Coleman Mach unit. At those temperatures, the second compressor should have kicked in. Are you on a 30 amp lot by any chance?? At 13A only one compressor is running and cooling will be very limited. This unit usually has one 1 compressor on each leg, L1 and L2, on a 50 amp RV, so 0A on L2 is the reason. But at this point I cannot help further other than to suggest that you take a peek at the control board, it has LED indicator lights on it which may give you a clue.

(I have the same problem on my unit that I will likely address next winter, no troubleshooting done yet so the best I can provide is general information right now other than to suggest that the relay on L2 (second compressor) (found next to the control board) may have failed, not an uncommon problem!!. You might try the Winnebago board for more informed answers or call Colemen Mach. They were very helpful to me last time I called.)

You could always change the DW for one that doesn't complain as much, that might help for now. ;D Heh heh

Great reply! 

Yes I have the Coleman Mach and I was hooked up to a 50A service. Everything else worked, but perhaps nothing else was drawing from L2.

I woke up last night and realized that this amount of current was probably running the hot water heater and the refrigerator and little else.  I have a Progressive surge protector,but it wasn?t putting out any error code.

This morning I fired up the generator and this A/C fired up just fine.  Tonight I will be in Bryce Canyon at a KOA so perhaps better 50 A power. If so I will start to wonder why the Progressive didn?t show a code.

 

[JoelP]

It seems I can rule the incoming power since I am now at a KOA in Bryce Canyon with the same issue.  I now believe that this must be related to the Powerline EMS.  It doesn't seem to be able to provide power to L2 despite the presence of power at the service outlet. While the LED readout seems to be showing that power is applied to everything (water heater, AC comp#2, fan speed and refrigerator), there is no current being displays on the Powerline panel.  My Progressive surge protector is showing 13A on L1 feeding various items like hot water heater, refrigerator, lights, fans and more.  However, it still shows 0A on L2.  I cannot find any other circuit that is failing to work.  Can it be that only the A/C is connected to L2?

My plan next is to take the Powerline cover off tomorrow and probe voltages.  It strikes me as strange that it shows no current on the Powerline readout panel.  Perhaps the relay for L2 is not functioning.

Any helpful hints on diagnosing this would be appreciated.  It is somewhat cool now in Bryce Canyon, but next come th4e Lake Mead area that will surely be very hot.

Thanks!

 

[Alfa38User]

Can it be that only the A/C is connected to L2?

Not likely!!

When looking at the circuit breakers on your RV power panel, you should see 2 rows of C/B. One row is on L1, the other is on L2. Which is which will not be easy to determine without opening the panel though. But if that Powerline panel also has a load shedding function, it could very well be the problem as an AC most likely goes through there so it can be shed if required

 

[JoelP]

Not likely!!

When looking at the circuit breakers on your RV power panel, you should see 2 rows of C/B. One row is on L1, the other is on L2. Which is which will not be easy to determine without opening the panel though. But if that Powerline panel also has a load shedding function, it could very well be the problem as an AC most likely goes through there so it can be shed if required

As you guessed it was not the Powerline.  I opened it up and there was 120V on both L1 and L2 coming out of the Powerline. This doesn't explain why the PowerLine doesn't show the current draw as it supposed to.

Next I will look under the bed (not much fun) at the backside of the service panel to see if I can decipher what is on L2 and perhaps something else will jump out at me. 

I confirmed today that the generator doesn't run the AC either.  It does put the generator under significant load by the way it bogs down, but it is impossible to tell how much current load is being exerted since the Powerline has no readout and the Progressive doesn't monitor the generator current. Sure hope to figure this out soon.

 

[JoelP]

Today I took the service panel cover off and lifted the bed to look at the backside.  The L1 and L2 lines to the A/C were both reading ~120V.  Next I pulled the cover off the heat pump control panel and there I found that a 30 microfarad electrolytic capacitor (probably a startup capacitor) had exploded, spreading a waxy material over everything.  I have to wonder why this might have happened, but my next step is to find a replacement to see if this is all it takes to get it going. Unfortunately, my attempts to find a capacitor like this in Panguitch, UT were unsuccessful, but perhaps I can find one in Las Vegas on Monday.

 

[John From Detroit]

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