This may have already been covered somewhere so forgive me if it has.My Coleman a/c which is 21 years old with very little use works great at night but when the temp is over 100 degrees in the daytime it blows cold for a few minutes then the compressor shuts of for a few minutes then come back on and starts blowing cold again. It will do this over and over and never cool trailer down. I was thinking perhaps it is low on freon but I read that they are a closed and sealed system. Could an rv tech check it if I took the unit to him?

What is the voltage in the RV? Low voltage is hard on the motor.Otherwise the cycling points to excess current through the compressor indicating the motor is about shot. At 21 years it would be OK to just replace the upper unit.

An R/V tech will tell you that you need a new A/C so be sure the guy you calls is also willing to replace it or you will have to pay a 2nd service call from someone who will. There's almost nothing to check other than to see if the fins are cleans and the inside filter is clean. If you can get on the roof you can do this yourself. You can't recharge the unit. There is a slim chance it could be the start capacitor but I don't think it would make any difference if it was hot or less hot outside.

Does the evaporator have frost on it when it stops working?

time2roll wrote:What is the voltage in the RV? Low voltage is hard on the motor.Otherwise the cycling points to excess current through the compressor indicating the motor is about shot. At 21 years it would be OK to just replace the upper unit.Trailer is plugged into the house so I'm assuming it has the full 120 volts. It doesn't trip the breaker in the house or the trailer.

Along with the other questions, what do you have for a power cord and where are you using it? If this is at your home on a lightweight extension cord to a 20 to 30 amp pigtail, it's likely the cord is getting hot and causing your voltage to drop.

A/C works at night only | Good Sam Community

24 Replies

RLS7201
Explorer II
Aug 07, 2018
marcsbigfoot20b27 wrote:
Yup my guess is dirty or low airflow at the condenser.

Exzactly, all the classic symptoms of a dirty condenser coil.

Richard
marcsbigfoot20b
Explorer
Aug 07, 2018
Yup my guess is dirty or low airflow at the condenser.
ksg5000
Explorer II
Aug 07, 2018
The std procedures I use when diagnosing my 26 year old Coleman air conditioner start with 1) check voltage 2) clean condenser and evaporator fins, clean filters, and visually inspect the capacitors. Older A/C tend to need more power to start up and many (including me) eventually add a hard start capacitor. Since your air conditioner seems to work fine at night it's likely that low voltage is the culprit - but cleaning the condenser and evaporator and filter will help regardless.
wa8yxm
Explorer III
Aug 07, 2018
Re Voltage (Plugged into house so I assume...) NEVER ASSUME. remember how to spell that word by puting a space either side of the letter U.

Measure.

I was at 105 and having all sorts of issues. No if you want to know how bad that was.. 105 on the OUTPUT side of a HUGHES autoformer.. We are well under 100 on the park side of that big heavy box.
time2roll
Nomad
Aug 07, 2018
2oldman wrote:
TravelinDog wrote:
Trailer is plugged into the house so I'm assuming it has the full 120 volts.
Plugged in how.. extension cord?
And is it a dedicated 30 amp circuit?

Standard 5-15 outdoor outlet can have significant voltage drop depending on conditions.

Easy to just put on the air and check voltage before it quits. No sense in slowly damaging the new unit.
Walaby
Explorer II
Aug 07, 2018
If it works at night, but not during the day, not sure it would be a voltage problem, since he's plugged in "at the house". Now, if at a camapground, and volage usage is higher during the day, that might make more sense.

But, I do agree, it would make sense to check it before replacing unit, rather than assuming. Simple enough of a check.

Mike
Lynnmor
Explorer II
Aug 07, 2018
Apparently he is going to replace the AC and not even check the voltage at the unit. Whatever.
2oldman
Explorer II
Aug 07, 2018
TravelinDog wrote:
Trailer is plugged into the house so I'm assuming it has the full 120 volts.
Plugged in how.. extension cord?
MEXICOWANDERER
Explorer
Aug 07, 2018
dougrainer wrote:
MEXICOWANDERER wrote:
You mean to tell me the expansion valve on these units is not serviceable?

EVERYTHING on the AC is serviceable. Just not cost effective. Especially a 21 year old unit. Its a sealed system. By the time you install a line tap and drain/recover the Freon 22, then replace any Freon part, and evacuate and recharge, just not cost effective. Plus Freon depending on where you get it(now it is $75 lb) and just takes 1 lb. Doug

Clear and concise. Thank you. The folks who installed a new ND compressor, condenser expansion valve and evaporator on my toad, did something wrong and left it doing 50-50 pump cycles @ 15 seconds.

A year later it starts and runs for hours without fault. Cold as can be. The only thing I could come up with is that they overfilled the system which leaked down to permissible level.
azrving
Explorer
Aug 07, 2018
I backed my truck up to the RV and put a rope around the AC in it's box and pulled it up long 2x4's. Also remove your ac vent covers to see if the tape on the ducts and hoses has deteriorated allowing cool air into the ceiling cavity