AC Failing????

[VeggieBullet]

1972 31 Overlander
The AC started just fine when we turn it on.
Blowing Ice Cold.
Once the thermostat turns the ac off because it got the the set up temp it seems to work just fine...BUT!!!
Once is time for the AC to kick back on there is all kind of weird noises...The lights dimmed out and it seems like there is a bad connection somewhere.
We tried to figured out what the issue can be and when it does it if we move the temp level to 60 it doesn't do it....so is the thermostat failing?
Just wondering if the thermostat can be replaced with one of the digital ones of
HD.
Any advise?
thanks

[VeggieBullet]

The ac stopped blowing.
So I removed the cover from the inside and just manually moved the fan.
It does spins freely, so I turned the AC ON and manually moved the fan and it did work for about 45 mins.
After that the knocking noises began again.
We have a very limited knowledge about ac but it was easier to track the noise with the cover removed.
It sounds like a relay trying to kick in and is coming from here...(see the pic)
Any idea?
thanks

[Inland RV Center, In]

Originally Posted by VeggieBullet

The ac stopped blowing.
So I removed the cover from the inside and just manually moved the fan.
It does spins freely, so I turned the AC ON and manually moved the fan and it did work for about 45 mins.
After that the knocking noises began again.
We have a very limited knowledge about ac but it was easier to track the noise with the cover removed.
It sounds like a relay trying to kick in and is coming from here...(see the pic)
Any idea?
thanks

Your describing a failure of the compressor to properly start.

Once the compressor turns off, a rest period of a few minutes is necessary to allow the high pressure of the Freon, to drop.

Once it drops low, like 100 psi or less, the the AC should start normally.

However, if after that pressure drops, the AC is still trying to start, but won't, then more than likely the compressor start capacitor is weak, or even defective.

Andy

[perryg114]

I would make sure that the AC unit is getting proper voltage. If you are running your RV off of a 14 gage extension cord plugged into a wall socket you may have a low voltage problem that is going to cause the compressor to struggle to get started especially if it was not long before it last cycled off and the head pressure is too high. This is addition to what Andy already mentioned. If you are below 100V you got problems.

Perry

[VeggieBullet]

However, if after that pressure drops, the AC is still trying to start, but won't, then more than likely the compressor start capacitor is weak, or even defective.

Hi Andy
So what are the parts that we are pointing at in the pictures?
They look like a kind of a board or a panel with 3 components.
Do you have any of the compressor start capacitor in stock?
Thanks
Gus

[VeggieBullet]

Originally Posted by perryg114

I would make sure that the AC unit is getting proper voltage. If you are running your RV off of a 14 gage extension cord plugged into a wall socket you may have a low voltage problem that is going to cause the compressor to struggle to get started especially if it was not long before it last cycled off and the head pressure is too high. This is addition to what Andy already mentioned. If you are below 100V you got problems.

Perry

Hi Perry
Thanks for the input.
We are indeed connected to a wall socket (20amps) but there is no drop in the voltage.
Any other idea?
Thanks

[Alumaholic]

Therein lies your problem.
It may run on 20 amps, but you need 30 amps to start the AC.
That's why your starting capacitor is struggling.
You are shortening the life of your unit.

[VeggieBullet]

Hello Alumaholic.
Just wondering on the need for the 30Amp.
We know that it should be ideal.
Checking of the behavior of the drawing of amps as well on watts we only see 18 amps and no more than 1800 watts. Of course we don't run anything else while the unit is on.
So is this still an issue?

[perryg114]

It should run fine on 20A as long as there is nothing else loading the system down or another source of resistance. What was the voltage measured at the unit? The question is how much cord is between the trailer and the wall socket? Start capacitors do go bad and that will cause the unit to have trouble especially under load. It may well be the compressor is shot. The voltage needs to be measured under load and preferably the current as well with an amp probe. You can get a cheap one at harbor freight. The probe just clamps around the neutral or the hot but not both. You can get new caps at Grainger or some electric motor place. If someone over charged the unit it might also cause problems. If there is a Freon tap on it somewhere that looks like a clamp with a shrader valve on it then someone has tapped into the system and added Freon.

Perry

[VeggieBullet]

Hi guys.
While we are looking into the option of installing a 120V 30A we noticed this.
When turning the AC On with the Fan on High. there is no issue with the AC.
Any particular reason why this can be?

[perryg114]

You don't have enough air flow. You Evap coil or condenser is blocked. If there is not enough air flow through the coils it can really screw things up. High fan is always best to get good air flow but you probably have a restriction. If the air coming out is more than 20 degrees cooler than the intake you may not have enough flow through the evap coil. I can be dirty or filters clogged.

Perry

[VeggieBullet]

Originally Posted by perryg114

You don't have enough air flow. You Evap coil or condenser is blocked. If there is not enough air flow through the coils it can really screw things up. High fan is always best to get good air flow but you probably have a restriction. If the air coming out is more than 20 degrees cooler than the intake you may not have enough flow through the evap coil. I can be dirty or filters clogged.

Perry

Hi Perry thanks for getting back to us.
So do you think that this whole thing can be due to these factors?
Only thing that We ever did to the other AC unit was to take the cover and with a paint brush with water and soap make sure that everything was neat & clean.
Is it time you think for a major AC maint? We are big fans of DIY for the main reason that nobody else will care much us we will. Plus unfortunately is getting harder and harder to find hones people. the whole thing of people trying to sell parts and services that are not need it's been a big
disappointment