Buick AC replacement and diagnostics

[Adam]

Hello all. I’m a long time fan of ETCG but first time poster so if I do anything wrong let me know.

I drive a 2001 Buick Century 3.1L V6. About a month ago while driving home from work at night I noticed mist coming out of my vents. The temperature was roughly the same as usual except there was a lot of moisture in the air coming out. I turned the air off and then turned it back on again a minute or so later and it wasn’t doing it anymore. About two days after that I went to use the AC again and I heard a grinding noise. When I did a quick visual inspection I saw that the compressor clutch was trying to engage but just wasn’t spinning the compressor. I have since replaced the clutch thinking it was just worn out from 15 years of use. Same problem. I am now thinking about replacing the compressor. I know how hard AC work is and I realize that I would also need to replace the accumulator and all the seals on the system. I’m a fairly experienced DIY guy so I’m not afraid to tackle this job. I just really don’t want to spend $300+ on parts if that’s what I need. I really feel like this is mechanical failure but I went ahead and checked my pressures today and took a picture because the reading I got made no sense to me. I will attach the picture to this thread.

Any help with this would be greatly appreciated. Also I realize how tough AC work can be so if it’s best left undone I’ll understand, although I do live in the south and the summers are brutal lol. Thanks in advance.

Topic

[Andrew Phillips]

Before you condemn your A/C system, let’s try this approach.

You live in the South. The air is hot and humid. The A/C has a natural effect of dehumidifying the air. The evaporator case has a drain for the condensate (condensed water vapor) produced by this effect. The drain allows this water to be expelled outside of the vehicle onto the ground. This is why you can see cars that have just parked developing small puddles of water in the summer when they’ve been running their A/C. This drain can get clogged up. When that happens, the water cannot drain as fast as it should. The evaporator is cold enough to freeze this condensate that cannot drain and creates this mist. If the drain continues to fully clog, the water will eventually find a way out of the evaporator case and onto the carpet inside the car, especially on the passenger side below the glove box area, since that is where the evaporator is usually found. To repair this condition, crawl under the car (sometimes you can see it from the top) and look near the firewall on the passenger side and find the A/C drain. It should look like a rubber elbow that is open on one end and hanging down. Pull it off and inspect it for a clog. If water begins to drain out, that’s a sure sign that you’re making progress. Water doesn’t always drain out, though, especially if it has been a few hours or overnight since the A/C was run.

There are two other possibilities for the mist.
1) The heater core has developed a pinhole leak and engine coolant is causing the mist. However, if this were so, you would notice the distinctive smell of coolant and the mist would feel somewhat oily and lay a film wherever it settled. The carpet would also become moist, but unlike in the previous description, it would feel oily and again smell of coolant.

2) The evaporator core has developed a pinhole leak and refrigerant was escaping causing the mist. This can also have a somewhat sweet-smelling acrid odor, but if the leak was small enough it may not have been noticeable even though there was some fog. This is easy to check by placing manifold gauges on the system and reading the system pressure (I didn’t see a picture that you mentioned you would attach). If the static pressures on both high and low sides (with engine and A/C off) are around 100 psi, the charge is fine and the refrigerant was not leaking. If the pressure is low, or zero, then the refrigerant has been lost, the system needs to be leak tested and repaired prior to evacuation and recharge.

As for the compressor, I think this is coincidental but not related to the mist you described, unless caused by a refrigerant leak. If the compressor seized up and won’t turn when the clutch locks it, one of three things should happen: 1) The clutch will burn from friction producing smoke and a foul odor, or, 2) the belt will slip and cause a loud screeching noise, or, 3) the engine will stall and may even throw off the belt. You should be able to turn the center of the compressor with the engine off and clutch disengaged, although there should be some resistance due to compression action in the closed refrigerant loop. If you take a piece of wire and jumper the load side (contact side, not coil side) of the A/C clutch relay while the engine is running and A/C is turned on, does the compressor engage and turn now?

You described ” When I did a quick visual inspection I saw that the compressor clutch was trying to engage but just wasn’t spinning the compressor.” Can you elaborate on that, please? We can fix this together, if you want to try, but you will need to be my eyes and hands and help me understand the things I cannot see or touch for myself.

[Adam]

Thanks for the help cap269 I’ll be sure to check your suggestions out.

Sorry about the picture I thought it had loaded but I can tell you the pressures were 104psi on the low side and 110psi on the high side so there’s definitely no leak in the system. I was just concerned that the low side was too high and the high side was too low.

As far as the compressor clutch goes, what happens when I turn the AC on is that the clutch engages for about 2 seconds and just grinds away on the compressor without spinning it then releases. I get the feeling that this is a safety feature so that the clutch doesn’t stall the car or throw a belt. It will shoot sparks and smoke for those 2 seconds then release for couple of seconds and try again. When it does this there is a very noticeable change in the idle. I’ve only tried it while the car is parked because I don’t want to cause any more damage.
I tried turning the compressor manually with no success.

I will be doing a closer inspection of the drain as well as checking under the floor mats for any buildup of coolant. It has been a few weeks since I’ve been able to run the AC so if it was just water it would be gone by now.

I think that should answer all of your questions and thank you again for the suggestions. I’ll be working all day tomorrow so I won’t have time to get under my car but as soon as I can I’ll get back to you with what I find.

[Andrew Phillips]

[quote=”ishmael86″ post=143990]the pressures were 104psi on the low side and 110psi … I was just concerned that the low side was too high and the high side was too low. [/quote]
No, that’s a fairly normal static pressure reading when the system has a good charge but isn’t running.

I turn the AC on is that the clutch engages for about 2 seconds and just grinds away on the compressor without spinning it then releases. I get the feeling that this is a safety feature so that the clutch doesn’t stall the car or throw a belt. It will shoot sparks and smoke for those 2 seconds then release for couple of seconds and try again. … I tried turning the compressor manually with no success.

Not a safety feature, just a very wide clutch gap and its slipping…badly (refer to symptom #1 of a seized compressor in my previous reply). Not being able to manually turn the compressor suggests that it has actually seized up and will need to be replaced. You will also need to replace the accumulator and orifice tube. If it has sent metal through the system, you will also need to remove all of the lines and flush them with mineral spirits followed with a flush of acetone or compressed air to dry them. If metal from the compressor has gotten into the condenser it will have to be replaced as well. You’ll know if this is a possibility based on how the orifice tube looks. If it doesn’t have metal in it, then the condenser is probably ok.

[Adam]

cap269, I wanted to update you on the situation.

I took out the orifice tube and checked the screens and didn’t find any metal. I also took off the compressor since I had the system evacuated to check my air gap on the clutch as well. The air gap was .0030in so it’s within spec but the compressor still won’t turn. I also looked inside the compressor (as best as I could) to look for any metal shavings inside the compressor and didn’t find any in there either. The whole system is original parts and the car came from Florida originally and is now in NC so it may just be overused and beat up.

I know OE is always the best bet but if you had any recommendations on reliable parts it would be greatly appreciated.

[Andrew Phillips]

I’ve had good experience with Four Seasons brand when not using OEM.

[Author]

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