Auto A/c question

G

gunslinger

My brother has a 2000 maxima. The a/c was working fine up till a few weeks ago, when it started to blow warm air, that lasted a day, then went to back working normally. A few days ago went back to warm air, and has been like that.

He just moved and doesnt know a reputed repair shop (oxymoron?). Anyway before they tell them the compressor needs to be changed, does this sound like coolant probs. or is the compressor the obv prob?
 
Coolant? You're suggesting the coolant in the radiator affected the a/c unit? What did the temperature gauge say? Was the car overheating?
 
It could just need a recharge of the refrigerant as a temporary fix but if it is leaking the stuff something needs fixing. There are electrical controls for engaging the pump, maybe those have gone flakey but not likely, most likely thing is a leaky hose or pump. Put a crowbar on the wallet, ask around for a good mechanic recommendation [there are a few in every town] and invest in a professional diagnosis, anything else is speculation. Even if it is low on refrigerant it takes a pro to charge the system up without destroying something.
 
Quote from Ivanovich:

Coolant? You're suggesting the coolant in the radiator affected the a/c unit? What did the temperature gauge say? Was the car overheating?
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Not coolant, I meant,,,whats the tchnical term, oh yeah, the stuff that makes the air cold
 
If the system needed a recharge, or the compressor was bad, I doubt it would have "started working again".

Low charge levels will cause the compressor to cycle frequently, then a pressure switch will eventually shut it down until it is recharged. But I would think that warm air would blow during this phase, and cooling would not start again.

Your brother should check if the compressor is being engaged. The pully will turn regardless, but you should be able to see the shaft turning when the electric clutch engages. Check the wires leading up to the clutch area for tightness. The clutch should make a "clunk" sound when the compressor is engaged.

A low fluid condition would usually mean the system has leakage, probably from the compressor seals. I've had good luck with the "lube/recharge/seal" type stuff you can put in with a simple gauge set. Got mine at Walmart. Still working 3 years after the shop said to me "you need a new compressor". This may be a good method to try, especially if the car is going to be sold soon!

Your results may vary. Good luck!
 
Quote from maxpi:

It could just need a recharge of the refrigerant as a temporary fix but if it is leaking the stuff something needs fixing. There are electrical controls for engaging the pump, maybe those have gone flakey but not likely, most likely thing is a leaky hose or pump. Put a crowbar on the wallet, ask around for a good mechanic recommendation [there are a few in every town] and invest in a professional diagnosis, anything else is speculation. Even if it is low on refrigerant it takes a pro to charge the system up without destroying something.
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Agreed, but mechanics are somewhat notorious for estimating to the highest repair. He just wanted to know with those symptoms is it always going to be the compressor
 
Quote from Wayne Gibbous:

If the system needed a recharge, or the compressor was bad, I doubt it would have "started working again".

Low charge levels will cause the compressor to cycle frequently, then a pressure switch will eventually shut it down until it is recharged. But I would think that warm air would blow during this phase, and cooling would not start again.

Your brother should check if the compressor is being engaged. The pully will turn regardless, but you should be able to see the shaft turning when the electric clutch engages. Check the wires leading up to the clutch area for tightness. The clutch should make a "clunk" sound.

A low fluid condition would usually mean the system has leakage, probably from the compressor seals. I've had good luck with the "lube/recharge/seal" type stuff you can put in with a simple gauge set. Got mine at Walmart. Still working 3 years after the shop said to me "you need a new compressor". This may be a good method to try, especially if the car is going to be sold soon!

Your results may vary. Good luck!
More...

Ty, if low fluid, are the items from WMT easy to install?
 
THis may not be the "recommended" way to fix auto a/c, but it has worked for me. My system was actually opened while the shop troubleshot the problem, so there was no fluid in there.

They quoted something like $400, but I had put in a new compressor 2 years ago (was definitely bad then). Anyway, I got the stuff from wal-mart and recharged it myself. Ideally, and for a "good" vehicle, the system should be flushed and a vacuum pulled on it to remove any contamination and water vapor, THEN new fluid put in. The "Drier/Accumulator" and expansion valve/orifice tube (if so equipped) should be replaced. Also, an exact amount of compressor oil should be put in. Mine still had the oil, so i was alright there.

It's pretty easy. There should be a schrader valve (like tire valves) on the "low pressure side" ONLY HOOK UP TO THE LOW PRESSURE SIDE (I'm pretty sure you need a different connector on the HP side, but it's been a while since I messed with it). Then follow the procedure on the "fill and fix" bottle. make sure you use the right stuff. Mine is R134A. Yours probably uses something else.

You start the system and watch the gauge pressure. Stop when it is at the recommended pressure for the current ambient air temp. That's it. If it is an older vehicle and your other option is an expensive repair, then i'd try it. Be careful under that hood! Watchout for moving parts.
 
Quote from Wayne Gibbous:


Your brother should check if the compressor is being engaged. The pully will turn regardless, but you should be able to see the shaft turning when the electric clutch engages. Check the wires leading up to the clutch area for tightness. The clutch should make a "clunk" sound when the compressor is engaged.
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definitely check this. This happened to my van. It was a $160 repair job (vs $600 for the compressor). They replaced the A/C clutch and coil. Compressor was fine.

In case you are wondering, the typical A/C unit consists of a compressor (where the cold comes from), and attached to this is a pulley, clutch, and coil. The latter parts power the thing.
 
There is a clutch cycling switch somewhere on the freon line that cycles the comp on and off. Follow the wires from the clutch on the comp to this switch. Its job is to shut the compressor down if the freon pressure becomes to low due to leakage. Sometimes the switch itself goes bad. Sometimes the freon level gets too low and the switch will act funky cutting the comp on and off. You can take a piece of wire and bypass the switch by jumping the connector. If the ac blows cold with it bypassed then it is the switch. If the ac blows hot with it bypassed then the system is low on freon. You can add it yourself with the kit from WMT or any auto store. The switches I have replaced have run between 10-40 dollars but being an import it may be more. They are easy to replace and screw on like a tire cap.
 
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