A/C troubles

[01cummins4ever]

So been fighting this issue with air conditioner since it got warm out and even the last year it was giving me fits, basically my compressor won’t stay engaged even if I have up to three cans of refrigerant from a completely vacuumed system. I have manifold gauges hooked up when charging and can get up to between 150 to 200 psi on the high pressure side and compressor will still cycle off and come back on periodically.( it will drop about 50 psi before re engaging) Sometimes it will not re engage and start blowing warm air, I can wiggle the wires by the compressor and it will re engage for a while but eventually it will quit again.

 

I know it sounds like bad wires but they look alright and it doesn’t matter which wires I move, it does the same thing. So am I chasing an electrical issue, or compressor going out? A clog somewhere? I can’t even seem to find a leak even though it has used a can of Freon in the past about every month or so.

Edited June 17, 2019 by 01cummins4ever

[Tractorman]

7 minutes ago, 01cummins4ever said:

I have manifold gauges hooked up when charging and can get up to between 150 to 200 psi on the high pressure side and compressor will still cycle off and come back on periodically.

 

What is the low pressure reading when the compressor cycles off?  If it is around 25 psi, that would be normal.  The compressor should cycle back on when the low pressure side rises to somewhere around 50 psi.  If the compressor still does not cycle back on as the low pressure side continues to rise well above 50 psi, then you may have an electrical problem - anything from a faulty pressure switch, AC relay, wiring, or even and faulty PCM.

 

One easy check for a faulty AC relay is to swap the AC relay with another good relay.  If the problem goes away, you have found your problem..

 

I believe the PCM controls when the AC compressor operates based upon inputs from various sensors. 

 

- John

[Mopar1973Man]

First off... Chase the leak. 

 

I typically place a vacuum on the system and then watch the lo side gauge for up to 5 minutes. If it drop any vacuum at all it has a leak. Now I typically go over to NAPA and grab a seal kit for said vehicle and end up rebuilding all plumbing connections. Then vacuum test again. 

 

Like for payment for having @Smarty Support watch MoparMom while I did my surgeries I converted his 1990 Chevy from R12 to R134a. After doing the vacuum test I found that the 2 o-ring in the compressor where too small. I had to dig in a different pile of o-rings and get ones just slightly thicker. Vacuum tested again and it held a perfect 27.5 inHg for over 5 minutes. At that point I recharged the system. Kind of glad I did this for him the compressor was complete out of oil. 

 

As for the compressor start and stop. This can be worked on after it charged. If the low side switch on the accumulator is failing you can simply unscrew the low side switch and replace. It has its own schrader valve and seal.  

 

As for recharging I always warm the vehicle up and do the recharge at the hottest part of the day. Gives better numbers on pressures and get correct charge. I just done a jeep down in Ontario where the owner was getting OK cool air. It was charged in the cool of the morning and was actually over charged. After I vented about 5 PSI off the lo side it got colder. Bringing the lo side down to 35 PSI. Vent temperature dropped to 32-35*F.

Edited June 17, 2019 by Mopar1973Man

[IBMobile]

 

 

 

[01cummins4ever]

14 hours ago, Tractorman said:

 

What is the low pressure reading when the compressor cycles off?  If it is around 25 psi, that would be normal.  The compressor should cycle back on when the low pressure side rises to somewhere around 50 psi.  If the compressor still does not cycle back on as the low pressure side continues to rise well above 50 psi, then you may have an electrical problem - anything from a faulty pressure switch, AC relay, wiring, or even and faulty PCM.

 

 

The low side is around  25psi at 75 ambient temp. I don’t remember how much the rise was until compressor kicked back in but will check it again when I can do so during the day. I have replaced the low side switch but no difference. 

 

5 hours ago, Mopar1973Man said:

First off... Chase the leak. 

 

I typically place a vacuum on the system and then watch the lo side gauge for up to 5 minutes. If it drop any vacuum at all it has a leak. 
@Smarty Support

 

 

 

It seemed to hold a vacuum when I did it, but will double check again, I just borrowed a cheap autozone rental,

 

3 hours ago, IBMobile said:

 

 

 

Yep I’ve read through that a few times, great write up I may change out the Orificetube next time I pull a vacuum

[IBMobile]

This chart might help.

 

When I was a @JAG1 we toped up the A/C system on his work truck using a chart like this.  JAG1 said it hadn't cooled for a year.  The compressor was cycling quickly and when we were done it stayed on all the time with the low side reading, I think, of around 40 PSI. 

[suraiya]

Why you didn't contact your local ac repair service? They must have a solution. When I was in Dubai, I had faced the same kind of situation so I contacted ac maintenance Dubai. They solved my problem very efficiently.

[dripley]

1 hour ago, suraiya said:

Why you didn't contact your local ac repair service? They must have a solution. When I was in Dubai, I had faced the same kind of situation so I contacted ac maintenance Dubai. They solved my problem very efficiently.

Most of here dont go to shops except as a last resort. We kind of rely on one another to help find the solutions for 2 reasons. 1 to save the money and 2 so we hope we did it right. Plus this is the glue that holds this place together,

Several years ago my company sent me to Missouri on a day trip. My project manager asked me if the AC worked. Well it had not worked for about 3 years and I told him I was fine I just roll the windows down and drive. That entire trip it rained and was 95 out the whole way up and back to NC. I jumped on here and had all the info I needed and rebuilt the whole system. The parts cost me $250 excluding the evaporator and has worked fine ever since, That would have cost me 7 or 800 bucks. The system is pretty simple unless you have to chase wiring issues. I despise wiring issues. The mechanical is easy for me.

Not knocking your advise. All depends on what you want tackle. Plus Dubai is a bit of a long drive.

 

[That Guy]

You can put a jumper wire in the connectors for the switches to see if it is the switches. Monitor the pressures for any funny business. Feel the relay, warm is normal, burning hot isn't. If the compressor starts to go, they typically start getting hot. Slightly uncomfortable is normal 100-130*, burning is not 150*+. 

 

The high side shouldn't cut out till 500 psi, kicks back in at around 400. Low has already been said. 

 

What is vent temp?

 

If O tube is blocked or starting to, you will see very low on the low and very high on the high side. If it is blocked, you will likely have other issues to address in the system like a failing compressor or burst desiccant bag in the dryer. Both would require a system flush at minimum thought I personally just prefer to replace everything but the lines. Typically the cost of having a shop do a flush is more than the cost of the evap and condenser, and warranties are no good on stuff unless shop does the flush with receipt.