A/C and Cooling issue

[omegared19]

So a lil while back, my a/c stopped working on my 1996 Saturn SC2, manual tranny. the clutch wasn't engaging, so I replaced the compressor with a brand new on. When I turned the a/c on, the new compressor clutch still is not engaging and the fan is now not turning on.

Shortly after this, the cooland was boiling over out of my coolant reservoir (which was brand new). I've since tried replacing the t-stat, radiator, and ect sensor. The temp gague is ancting normally, and the fan is kicking on at 3/4. All my relays and fuses are good. This seems to be a common problem on here with freeway and city driving.

I'm narrowing the problem down to PCM, fan, or (god help me) the head gasket. Tho I'm not getting any white smoke.

People are saying the PCM is about as likely to go out as I am to winning the Lotto.

The fan might be an issue, but why would it still come on at that normal temp?

Are the A/C not working and the temp going excessively high related? How can I fix both? (even if it needs to be done seperately)

[fdryer]

1-First of all, does the cooling fan (original @16yrs old?) bring temps down as seen on the temperature gauge? If not then replace the fan as its crucial to cooling system temperature regulation. Even more important if you want the a/c to work.

2-When the a/c compressor was replaced, was it done correctly and fully restored cooling? Please explain the details as its important to determine how and where it may have failed.

With little information supplied, the loss of a/c cooling is most likely similar to 98% of all a/c system issues, a leak. Once a leak starts, the once sealed and pressurized system has leaked out most of the refrigerant - so much that the pressure sensor has detected too much is lost and sends a disable signal to the pcm to prevent the compressor from powering up. If allowed to run with too little R134a, no lubricating oil will circulate back to the compressor. Liquid R134a moves oil throughout the system and eventually returns back to the compressor to help with lubrication. No R134a = no oil lube = a compressor that will quickly destroy itself in short order. Find and fix the source of the leak to allow this system to remain sealed against pressure leaks and this system can be restored back to factory condition.

A system that's running in HOT and HUMID conditions will easily generate high side pressures exceeding 250psi. Any poorly done repair will simply leak out the moment the a/c compressor is turned on. A/c repairs are unforgiving of mistakes.

The cooling fan is only needed when the compressor is running; if the compressor doesn't run, due to a leak, then the pcm has already determined (from the pressure switch signal) that the cooling fan isn't needed so the fan stays off except when needed for the cooling system.

[omegared19]

I appologize for the lack of info on the a/c system.

I did the replacement, but had the system pressure tested at a dealership. So I'm assuming that would check for leaks. I will admit that I also had them drain the system to pull out any freon so it wouldn't just leak when I did the swap. But according to the bottle of freon I bought, it says to engage the a/c clutch in order to get it to pull freon into the system, which is why it's been empty.

1) should I just put the freon into the system, per the instructions on the bottle, regardless? And is there a button/switch I need to hit in order to let the PCM know that the system is ok?

2)could the a/c not working, and the fan not coming on when I hit the a/c button, cause the overheating with the coolant system?

[fdryer]

Please answer question #1 about the cooling fan. If the fan won't bring temps down then the a/c repairs won't work correctly as more heat is generated in the condenser coils that adds heat to the radiator. A worn out cooling fan won't blow or suck with any force through the condenser and radiator if both are hot. This will cause the a/c to run erratically; in local traffic the a/c won't cool correctly but will at high way speed from forced air flow.

Repairing the a/c system according to you seems confusing. To start, replacing any parts on the a/c system means opening it. Removing any remaining refrigerant and replacing a major part like the compressor entails more that just putting in a compressor. The old compressor is drained of oil to measure the amount for pouring in new PAG oil into the replacement compressor. This balances the oil system any time parts are replaced. Did you use new O-rings lubed with R12 mineral oil or Nylog? Pag oil is not recommended for O-ring lube as it will corrode the fittings. After this is all done, was the sealed system evacuated of all air and moisture with an electric vacuum pump designed for a/c repairs? Not evacuating a repaired system leaves air and moisture to contaminate a repaired system to compromise it forever besides causing new issues. Once a total evacuation is done with gauges to monitor everything for at least 30-minutes, the pump and valves to gauges are shut off to monitor any leak back from atmospheric air going back into this vacuum. Only a vacuum should remain with the gauges not showing any decrease in vacuum readings - this ensures a correct repair and the system should hold pressure when refilled with R134a. Once a vacuum is determined to hold, then and only then is R134a injected into the system. R134a and Pag oil are the only two components allowed to freely circulate in vehicle a/c systems. Any opened system that undergoes repair cannot be refilled with R134a until its evacuated of all air and moisture. To do otherwise is courting disaster later down the road after the repairs. Although cooling may take place immediately and for some time after, sooner or later, the air and moisture that already contaminated the system will ruin it by chemical reaction to refrigerant and oil. A slow death will result and destroy the system from within, sight unseen. Not evacuating a repaired system is amateur work and not acceptable when vacuum pumps are available for removing all traces of air and moisture. No a/c repair is complete until a total evacuation is done.

A repaired system that holds pressure means a leak won't occur. A leak means that during a/c operation, pressures can easily exceed 250psi on HOT and HUMID days. A leak is the first weakness in a system that will release 250psi of pressure easily. Not many are aware of operating pressures and what a leak does under high pressure. A correctly repaired system that will hold pressure will not leak. Idle system pressure, when filled with the correct amount of R134a, will always be above the minimum required to trigger the pressure switch that disabled the compressor when a leak occurred. Standing pressures will vary from 50-90psi depending on outside temperatures. This will be more than enough to overcome the pressure switch to allow power to the compressor. Half a pound of R134a is sufficient to turn off the pressure switch to allow the compressor to run.

A/c repair is unforgiving of mistakes. Whether you know it or not, you are well into advanced a/c repairs and any small mistakes may be costly ones. Tread lightly unless you are fully aware of refrigeration repairs. If you are not equipped to finish repairs with evacuating the system using gauges before recharging the system with R134a and any make up oil then let a reputable a/c shop finish it.

[caveeagle]

Do youself a big favor........... Reread fdryer's posts and listen to his advice!

could the a/c not working, and the fan not coming on when I hit the a/c button, cause the overheating with the coolant system?

I would add, that your a/c issues should not be causing your engine overheating issue. Your cooling fan kicking on at 3/4 is normal. The fact that your colling system is not capable of cooling your engine back down is telling you that is another issue.

Your electric cooling fan is almost certainly at fault (at least partially). It is super easy and cheap to get a new fan motor from a local parts store and swap it out. From there, its just radiator, water pump and thermostadt. It should be pretty easy to figure out if those are all working properly.