Hey guys. So I stopped my leak after replacing o rings and top gasket on compressor. After filling it and running it, it is noisy, and also drags down the engine's rpm as though it's struggling to turn.
It's cooling fine, but it is raising the engine temp. My car usually runs in the 230 range...at the most. Now she is going over 245!
The noise is not screeching or sqealing, but more like a dry bearing sound (?) Clutch is engaging, and staying engaged like normal. Is there a bearing that can be replaced without draining the system?
Any help is appreciated.

Pat
1989 C4 Coupe

 

 

I will check the pressure 2morrow. I actually had a shop fill her, so I hope their Snap On machine did it correctly.

Thx, Pat

 

The ecm should compensate and keep the idle speed the same as without a/c on, did you recharge by refrigerant weight or just added some?


Did you evacuate the system with a vacuum pump before charging it?
If the engine is bogging down then you may find the head pressure quite high.

With R12 you can overcharge a bit however R134A is critical only needing 80% of the R12 gas charge weight. Overcharging R134A will raise engine temp and test the rubber hose limits.

With too much refrigerant (R12) the compressor will be trying to pump liquid and get quite noisy, the compressor can lock if bad enough.

Don't try to guess it...

 

Gerardvg I actually had a shop vacuum n refill her. I replaced hose o rings and main gasket on top of compressor too. He has a Snap On machine that did the vacuum and fill. I was there when he did it. The machine ran it's own tests. One thing I thought was weird though...the fill process was done with engine off.

 

When under a vacuum it is easy to fill with the engine off. Just set the refrigerant tank on a scale and fill by weight. I've done it may times in the past and it works great as long as you know the correct amount the system needs.

 

Hi

Yes no problem charging the a/c with engine off, the correct R12 charge weight is in the engine bay on the a/c evaporator /fan box.
R134A will need only 80% of the R12 charge.

It may just be a bad compressor.

 

Yah, charge looks correct. Not happy at all with temp, running over 240! Just might have to bite the bullet and get a new compressor!

 

My truck compressor is new and it growls when I first turn it on. I think I put too much oil in it. Could that be your issue too?

 

When I turn my compressor on it hards starts too. Once it is running it's fine. I think its just how the new compressors are. I wish the car cooled down better. It still doesn't get colder than 68* according to my vent thermometer. When they were filling it at the shop the machine they used to fill detected a leak but, they couldn't find the leak and I never lost the charge. I just deal with it now but, I would like to get it working properly and not just "okay".

 

I doubt it. The shop used a Snap On unit to vacuum n fill. When the compressor is running, the car lacks power n runs way to Hot!

 

Yah, I've been "dealing with it" too long now. I got sock, so I rrally need cold air these days...

 

And you are certain they didn't add oil?

 

From what I remember, he did add the pag oil. Would that affect how it runs? I would think it would help quiet things down...

 

Too much oil (as is the case with mine) has the compressor working like a hydraulic pump. It struggles to push all that oil around. I know that mine is straining and I feel the diminished performance. The initial engagement is rough. Then it runs pretty normal and is cold enough. I can't speak to the increased temps since it is a totally different vehicle.

I'm just unmotivated to take the thing apart again. It was a sumbitch.

It's a beater truck so I'll run it till it dies. I would not have that attitude with a Corvette.

 

Hi

PAG oil should only be used on new systems like new compressor condenser or hoses, it will not mix with any mineral oil.

Ester oil is what is recommended for R12 to R134A conversions, you cannot remove all the oil from the compressor.
That's why its best to use the mineral compatible oil, and not overdo the oil fill.

It could be overcharged, that would explain the high engine temp and engine laboring .... Does the cooling fan cycle on and off or stay on?
My 85 has the 88-91 a/c compressor running R134A and coolant stays 190F (i run a adjustable temp switch) only going up to 230F when idling for long periods in traffic, pops right down when moving again.

Have you checked the space between the radiator and a/c condenser?
That can fill up with leaves and plastic bags, our cars are highway vacuum cleaners .....

I think from memory my suction pressure runs at around 35 to 40 psi,
the head pressure will cycle 230psi open and ecm will run cooling fan.
180psi the switch closes and ecm turns cooling fan off.

It is the small round plug next to the high pressure safety which has two spade terminals, removing the small round plug with engine running will result in cooling fan turning on.

The large round compressor cycle pressure switch is on the exit of a/c box in engine bay low pressure pipe to hose that runs to accumulator and then to compressor.

The small alloy pipe with the a/c high pressure cutout and cooling fan request switch, feel the temperature of that where it goes to the orifice tube and a/c box. It should feel warm to hot, but not too hot to touch
230psi it should be at 42 deg c (around 108F)
If its way too hot that means your pressure is too high, slowing the engine to almost stalling before the high pressure switch cuts the a/c off.

Best to check it with cold engine so you are only using the cooling fan for a/c pressure control, confirm the fan cycles on and off and that small alloy pipe is not too hot to touch.

Doing those tests will help determine the problem, be it over charged or failing compressor or slugging too much liquid back to compressor.

I think the 89 should hold 36 ounces R12, so should only need 30 to 31 ounces R134A. It would need to be way overcharged more that 36 ounces R134A to drag the engine rpm down and coolant temp up...

Good luck

 

Gerardvg, man I feel sheepish.
I had to visit this shop twice. Before I went the 1st time I replaced o rings. He vacuumed out system, then it failed pressure test. Turned out the 2 o rings on compressor were the wrong ones. Left shop to find correct ones. Came back, installed new ones. Vacuum, passed pressure test, filled. When we started the engine and cycled compressor, it blew the top gasket/ring! Sent on my way again after he vacuumed all the freon back out.
I replaced the gasket/ring and went back a 2nd time (he was only gonna charge me an hours labor total between both visits, $85). So, he ran the vacuum, pressure tests then filled system. Started engine and began to cycle compressor but it kept turning itself off (would'nt syay running). Turns out aux fan wasn't kicking on. He had me take car around the block to confirm airflow would help compressor stay on and it blew cool air.
He told me to wire aux fan to a switch (I know, it sounds crazy to me now that I'm typing it), and sent me on my way. Well, I wired it to switch and it does work, but coolamt temp going as high as 245! I know it is probably a sensor/switch not letting compressor run, thus not turning on fan, right? At this point, I monitor coolant temp, and turn ac off if it's getting too high. I'm just happy I have cool air...
Pat

 

funny my 84 was converted to r134 and my low side stays about 50 psi its really cold

 

I have to agree with Gerardvg. First thing I thought when you said it was really bogging down was too much oil in the system.