A/C recharge issues

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Aug 12, 2004 | 01:04 AM

Diggie

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From: Prince George, BC

A/C recharge issues

Ok, had cycling issues with compresspor, went to shop they said it was low on coolant. Had it evacuated, no more cycling issues. In fact the compressor wouldn't even turn over. Purchased a Redtek re-fill kit, installed 134a adapters, fired up truck with A/C on max like the instructions said, and started to fill the system with the stop leak that comes with the kit. This took about 45 mins to empty one can into the system and during this, the compressor started to cycle again. Finished system off by adding the remaining two cans that come with kit. The compressor stopped kicking in. I have preassure at both the high and low sides, (sorry the gauge that come with the kit won't fit the low side nipple so I don't actually know the correct pressure) Wife starts to fiddle with A/C controls inside truck and viola the compressor kicks in, the air is extremly cold. Shut truck off, turn back on, no compressor at idle or while driving, no cold air. I have not been able to recreate since. Is it possible that the low preassure switch failed during the re-charge?

Sorry for the long post, just trying to be as clear as possible.

TIA, Diggie

Aug 14, 2004 | 04:23 PM

Diggie

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From: Prince George, BC

Update and new problem - Help!!

OK system was working for one day, 38psi on the low side and blowing faily cold air. Then the compressor stopped kicking in, I checked the pressure and with the compressor not running I had abot 80psi on the low side, the confusing thing is when the compressor does decide to engage the pressure drops back to mid 30's. Without the compressor running there is about 100psi on the high side. Jumping out the low side switch does not always cause the compressor to engage. Disposable oil analyzer shows good color and wetness.

Any ideas? If the compressor was seized would I know it?

Aug 14, 2004 | 10:35 PM

Pikachu

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From: Amarillo, TEXAS!

Probably wouldn't hurt to put a meter or a test light on the clutch coil leads to see if it get is getting energized. If it is, the clutch is the culprit. If not, you can start testing the pressure switch(es), and backtrack until you figure out where the power starts and stops. It isn't unheard of for a pressure switch to quit working. If the compressor is siezed, you can't turn it over by hand (not the pulley, but the center part).

Aug 15, 2004 | 12:14 AM

Diggie

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From: Prince George, BC

Thanks for the reply Pikachu,

With the low side pressure switch hooked up (not jumped) I get positive voltage to the compressor's wire harness when the A/C selector is moved between off and max or norm. When the truck has been siting for a few hours and started the A/C works fine, cycles normally but after a while it won't engage and the unit blows hot air. Sometimes this happens after about 15mins and some times the A/C will run for about an hour. If I let the truck sit for a while, and then fire it up, it works fine for the next little while.

Would air in the system cause conditions such as this?

Also, is it normal for the low side pressure to climb up to 90 or so psi while the A/C is shut off? (truck running). Once the A/C kicks in the pressure drops to 38psi with an ambient temp of 92deg F.

Thanks in advance

Aug 15, 2004 | 09:25 AM

Pikachu

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From: Amarillo, TEXAS!

OK. Try putting the meter on it again when it is warm and giving you problems engaging.

You ask about air in the system; if the system hasn't been open to the atmosphere, there shouldn't be any air in there....

Finally, yes it is normal for the low side to rise when the compressor isn't running. A/C systems, when running, operate with two different system pressures. When the system us off, the two sides equalize. With the compressor engaged, 38 on the low side is about right. I suspect this is going to end up being an intermittent electrical problem. Not fun to isolate....

Aug 15, 2004 | 12:13 PM

Diggie

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From: Prince George, BC

Thanks again Pikachu, I just wasn't sure about those numbers and the guy that evacuated it for me wasn't sure either, he's a general mechanic that happened to have a pump and a set of gauges. He suggested air in the system but I had to question that as it has not been open to the atmosphere since I have owned the truck.

I have tried the meter on the compressor when it is not working and I do have voltage there. Is it possible that the wiring inside the compressor is bad?

And I guess that at that point it is replace the compressor or at minimum take it off and re-wire it, then evacuate and re-fill.

Thanks again,
Derek

Aug 15, 2004 | 03:18 PM

Pikachu

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From: Amarillo, TEXAS!

If you have power to the clutch, but it is not engaging, you can have the clutch replaced without removing the compressor. Most any A/C service center should be able to do this relatively cheaply.