AC quit blowing cold

[Picinisco]

Went out for the day leaving the AC running. On our return the AC was blowing warm. I switched it off, went on the roof, took the cover off, cleaned the coil which had just a little bit of dirt on it. When I put everything back together the AC ran fine. Not sure that the minimal amount if dirt was the cause. Any ideas?

[dougrainer]

john9Z wrote:

That means you have a Freeze sensor in the evaporator. If it is installed and functioning your AC CANNOT freeze up. You need to check the wiring where the Capacitors are located and the connections on the compressor for burnt ends. Since you had an intermitant fault it may be corroded/burnt ends for the compressor circuit. Doug

You're right on that one.

Well, I don't need your approval:B But I do appreciate the vote of confidence. Doug (41 years and still working as a RV Tech)

PS, you just joined, we have quite a few professionals on this forum. AND. some very knowledgable Lay people.

[john9Z]

That means you have a Freeze sensor in the evaporator. If it is installed and functioning your AC CANNOT freeze up. You need to check the wiring where the Capacitors are located and the connections on the compressor for burnt ends. Since you had an intermitant fault it may be corroded/burnt ends for the compressor circuit. Doug

You're right on that one.

[dougrainer]

Picinisco wrote:

opnspaces wrote:
Thinking more about it, if you're in AZ then you probably did not have a freeze up of the evaporator.

As dougrainer was asking, is your AC controlled by a wall thermostat or by controls up on the AC itself?

I was in Southern CA, with temps in the low 80s.

Controls are wall mounted thermostat.

That means you have a Freeze sensor in the evaporator. If it is installed and functioning your AC CANNOT freeze up. You need to check the wiring where the Capacitors are located and the connections on the compressor for burnt ends. Since you had an intermitant fault it may be corroded/burnt ends for the compressor circuit. Doug

[Picinisco]

opnspaces wrote:
Thinking more about it, if you're in AZ then you probably did not have a freeze up of the evaporator.

As dougrainer was asking, is your AC controlled by a wall thermostat or by controls up on the AC itself?

I was in Southern CA, with temps in the low 80s.

Controls are wall mounted thermostat.

[opnspaces]

Thinking more about it, if you're in AZ then you probably did not have a freeze up of the evaporator.

As dougrainer was asking, is your AC controlled by a wall thermostat or by controls up on the AC itself?

[CA_Traveler]

Turn off the charger CB and all other appliances. Check the voltage (both legs on 50A) which should now be very close to the pedestal. Now turn on CBs, A/Cs, HW etc and recheck the voltage. The US standard is 120V +-10%. Your A/Cs may/may not be OK somewhat below 108V and I've found it rather difficult to determine the safe operating range. Your mileage may vary.

CGs tend towards lower pedestal voltage especially 30A plugs and summer A/C usage. This is due to the overall heavy amp draw. Plus the NEC allows for derating (maximum amps vs total of all CBs).

Personally I would check the AC voltage right where it enters the A/C but safety should be the major consideration.

With all AC removed including inverters all terminals should be checked. If fact making sure they are tight should be a annual check. As RVs vibrate and bounce down the road they become less than ideal. This results in voltage loss and heat buildup. All as in cord connections, junction boxes, ATS, EMS, CB panel, inverters and gens.

[dougrainer]

Picinisco wrote:

opnspaces wrote:
How long were you on the roof? Is it possible the evaporator was frozen up and it thawed while you were cleaning the coils?

No ice. But the AC was blowing warm air so I feel that if it froze then it thawed when the compressor shut down. Is the system designed to do that and stay shut down until the switch is thrown and then start back up when switched back on.

NO, The dirt on top was not the cause either. Do you have a wall tstat or ceiling mount controls for the AC? Doug

[Picinisco]

wa8yxm wrote:


Well the best place is on the roof at the compressor connections but that is not practical

A good place in a 30 amp RV is any outlet
In a 50 any outlet on the same leg as the Air Conditioner

Plug in volt meters Designed specifically for this

Thanks. That is helpful

[Picinisco]

Lynnmor wrote:

Picinisco wrote:

CA Traveler wrote:
Low voltage? Could cause overheating and compressor shutdown. A voltmeter is your friend.

Where would I check the voltage

At any outlet. Best to have a plugin digital voltmeter operating all the time in a easy to see place. Turn off the air conditioner when voltage is down to 105.

Thanks. Never thought that could be an issue.

[wa8yxm]

Picinisco wrote:

CA Traveler wrote:
Low voltage? Could cause overheating and compressor shutdown. A voltmeter is your friend.

Where would I check the voltage

Well the best place is on the roof at the compressor connections but that is not practical

A good place in a 30 amp RV is any outlet
In a 50 any outlet on the same leg as the Air Conditioner

Plug in volt meters Designed specifically for this are around 20 bucks

This is a nice one
I have an older analog one from them with pass through outlet very nice.

[Lynnmor]

Picinisco wrote:

CA Traveler wrote:
Low voltage? Could cause overheating and compressor shutdown. A voltmeter is your friend.

Where would I check the voltage

At any outlet. Best to have a plugin digital voltmeter operating all the time in a easy to see place. Turn off the air conditioner when voltage is down to 105.

[Picinisco]

opnspaces wrote:
How long were you on the roof? Is it possible the evaporator was frozen up and it thawed while you were cleaning the coils?

No ice. But the AC was blowing warm air so I feel that if it froze then it thawed when the compressor shut down. Is the system designed to do that and stay shut down until the switch is thrown and then start back up when switched back on.

[opnspaces]

How long were you on the roof? Is it possible the evaporator was frozen up and it thawed while you were cleaning the coils?

[Picinisco]

CA Traveler wrote:
Low voltage? Could cause overheating and compressor shutdown. A voltmeter is your friend.

Where would I check the voltage