Trouble-shooting the A/C

[papademuchos]

We have a 2004 Jayco Greyhawk, 31SS.

Last weekend we had it at a campsite with a 30 amp plug in. After connecting, everything was working except the A/C. The fan doesn't run - nothing seems to work. We left the switch to On and Cool. About 2 hours later in the evening it kicked on and was working just fine.

Just now I fired up the generator (Onan 4000W) and tried to get it running. Again, nothing. Any ideas on how to trouble-shooting this?

[Diesel-Lover]

Get on your detective outfit and gear and start eliminating things one at a time. Number one, is the house battery does it hold a charge or does it go dead .... Voltage drops are also a major clue. I had a similar happening with my microwave, and it turned out to be a marginally alive house battery

[papademuchos]

I recently replaced the house battery, so I know it's good. Also, if the generator is running, how would a bad battery affect the A/C? Doesn't the switch start pulling power through the converter at that time? The microwave works... outlets work...

[Desert Man]

I have a front and rear A/C. On a 30 amp supply I can run one only. Onboard Generator, portable generator plug in.

[Desert Man]

AMEN

[twinboat]

If you have load shedding, next time try turning off the water heater switch.

It may have been heating the water for the time the AC wouldn't run. Once hot, the water heater stops drawing power.

[kwftlaud]

I had a similar thing happen to me. My AC stopped working.
I shut it down, and next morning I took off air filter to see if that was plugged.
Filter was fine.
I turned the AC on, and nothing happened, but I could hear the compressor kick on. Since I had the cover off, and I could see the blower fan, I could see it wasn't moving. I gave it a push and it started to blow, and, the AC worked.
I put the fan to ON ( instead of AUTO ) and the AC worked for the rest of the weekend.

Since the blower motor would not start on its own, I knew a capacitor might be bad. I took off the cover ( on the roof ) and I found 3 capacitors which I found out was 1) fan, 2) start 3)run. It took me a while to find the correct values for the caps as they were pretty rusted but I did find them and bought them on amazon for about $40. Installed them and now all is well.

If when you turn it on and it makes no noise at all, then I'd chase the power or the thermostat . If you hear any clicks or hums, I'd check into the capacitors. My unit was a 2001 Coleman. The caps were in terrible shape. Give them a look.

Kip
2001 Itasca

[papademuchos]

Thanks for your ideas. I don't have a 30 amp plug-in at home right now, so I'm testing with the generator running. Because of the genny noise, It's hard to hear anything else that you suggested to listen for. I'll try your other ideas though.

I did some more trouble-shooting with voltage. First I tested the breaker switches to make sure and they seem fine. When I connect the strip on the left (white wires) and each terminal on each breaker they all register 120 volts.



Next I tested voltage on the Thermostat:



A quick youtube video indicates I should be getting ~24 volts on these wires. Using a simple voltmeter, I put black on the red wire and red on each of the other wires. This is measure A/C voltage, right? I'm not getting more than 2 volts coming in on any of them.

If low voltage is the issue, how do I follow the path to finder out where the disconnect is?

[youracman]

I'm thinking you looked at a video associated with residential HVAC, perhaps? (24 volts AC is used there.) The vid(s) I looked at show that 12vdc power is used as a control voltage in RV T stats. SOoooo you should put your (DVM?) meter on DC. The ground lead of your meter should go to the blue wire on the stat and then the (Red) wire on your DVM should measure 12.3 volts DC or thereabouts when you touch it to the Red wire/terminal of the stat. When you turn the stat switch to cool, you should measure the same 12.3 vdc at the yellow wire's terminal on the stat. The heat sw should apply 12vdc to the white terminal, the high fan switch should apply the 12.3 vdc to the green wire, etc. If you do, in fact, have the 12.3 vdc at the yellow wire when the stat switch is on air conditioning your air cond problem is likely not with the T stat ......... unless it is intermittent, perhaps.

Good luck with the fix. I hope others who are more familiar with the wiring etc than I am will chime in.

[papademuchos]

Thank you for clarifying how the RV stat works. I Get about 1 volt from blue and red. The 20 Amp breaker goes straight to the a/c unit, right? Where does the power come from for the Thermostat? Directly from the battery? Or would it be routed from somewhere else?

[youracman]

Originally Posted by papademuchos

Thank you for clarifying how the RV stat works. I Get about 1 volt from blue and red. The 20 Amp breaker goes straight to the a/c unit, right? Where does the power come from for the Thermostat? Directly from the battery? Or would it be routed from somewhere else?

I see on my WBGO wiring diagram that at least one connector is involved on mine but I would hate to have to trace it. A call to Jayco tech support might be in order.

1. Have you removed the fuse I see in the pic to verify it has "0" ohms resistance? If the contacts happen to be marginal, just removing and reinstalling it could make a difference.
2. I would probably use a long piece of wire and run it from the actual battery ground post to connect to my negative meter lead and then measure the voltage on the red T stat terminal. Kind of academic, but it would be good to know if a grounding problem exists. If the ground (blue wire) is the problem you might be able to run a separate ground wire to a "local" grd/frame point......maybe.

Tough problem, wish I could be more help.

[THenne1713]

Thermostat/ settings, user error= first thoughts? But a few years ago, mine woudl not start one day, pulled circuit board from RETURN AIR PLENUM in ceiling, found/ tightened a loose push-on connector, (pinched the female on the wire end) reinstalled, all good since. Yours maybe similar simple issue? ALL 12VDC/ 120VAC POWER =off TO DO THIS TEST/ INSPECTION. Good luck.

[papademuchos]

Thanks Ed (youracman), I did your suggestion of using a long wire from the thermostat control to my battery. After some trouble-shooting, the problem is the red wire / power coming in. The ground wire appears to be fine. I pressed one end of my wire against the red wire and the other end on the positive post of my battery and the fan started up.
So my next task to follow the wire to see where it comes from and try to figure out the break.
I did check the fuse and it seems fine.

[OldWEB]

Originally Posted by papademuchos

Thanks Ed (youracman), I did your suggestion of using a long wire from the thermostat control to my battery. After some trouble-shooting, the problem is the red wire / power coming in. The ground wire appears to be fine. I pressed one end of my wire against the red wire and the other end on the positive post of my battery and the fan started up.
So my next task to follow the wire to see where it comes from and try to figure out the break.
I did check the fuse and it seems fine.

Power from the DC fuse panel goes to the RV furnace where you should find a Power/Reset switch (Possible outside panel) and then the power (positive) goes to the thermostat where it returns to the furnace through the "Heat" (white) wire when heat is called for. The following is copied from the 'net:

Coleman RV Thermostat Wiring Color Code

Coleman has created its own standard for color-coding its wires. The company uses the following colors in its thermostats- red, white, gray, green, yellow, and blue. These wires are connected in the following manner:
- white- goes to the furnace (WF)
- gray is for the low fan speed (GL)
- green is for the high fan speed (GH)
- yellow powers the AC compressor (Y)
- red is hot (R)
- blue is your ground wire (B)