95 Q45 AC Question

[DAEDALUS]

You can usually tell when the compressor kicks in because you can hear the clutch engage, the relay should produce a little bit of a click, and there should be a noticeable change in the idle. The compressor takes power, so the idle drops just a bit when it kicks in, but the ECU compensates by allowing more air through the IAC to bring the idle back up to where it was. But the idle sounds a bit more labored. Luxury cars have a much smoother transition programmed in than cheaper ones. You're not supposed to easily notice the AC running on a $50k car. Assuming the clutch is good on the compressor, you can also check the voltage across the clutch. Open circuit, the compressor is off; 12V (or 5, I don't have an FSM here) means the compressor is engaged.

It sounds like the problem is fixed for now. Sounds like the condenser fan relay was the problem, or maybe the compressor relay. Don't think they cost that much, maybe just replace them both and then see. Hafta weigh cost of parts and comprare to effort required to troubleshoot/relace. A $500 MAF deserves more scrutiny; a couple relays don't IMO.

[rsiwicki]

okay....I have been out of the country for the past 3 weeks on business (no pleasure unfortunately) and got back Friday night. I took the car up to Orlando (3 hours) on Saturday night and returned on Sunday night. I did not have a single problem with the AC during my 3 hour trip without any stops inbetween both up and back....but after I shut it off let the car rest for about an hour and then got back in the AC did not work until the car got moving again...as soon as the car moves after about 2 minutes cruising about 20+mph or more the AC works perfectly. I am going to try to get it to the shop this weekend as they are open on Saturday to see what the solution is.

[Q45tech]

The compressor run continuously when AC/defrost is on -----just it's internal displacement changes [automatically] by a factor of up to 10 based on the suction pressure [25-35 psi]........tries to maintain a narrow range of suction [low] pressure.................single wire on clutch [+12v] turns it on/off.

Now te HP required to turn compressor varies with its displacement, temp, and pressure. Obviously small drag in cooler temps/defrost vs 110F outside.

Not having a condenser fan operating [either relay or its motor failure [common with age]]...........will increase HP draw to turn compressor.

[jamesmost]

robmy a/c is wacky as well. compressor on the fritz my mechanic hot wired the valve in the compressor to remain open, it gets cool enough but not rockin think i am gonna score a used compressor

[rsiwicki]

thanks for the info Q45tech...I have only seen the condenser fan come on once while trying to figure out what was wrong by moving relays around. All the other times it does not come on at all including yesterday. It is hot now here in Florida and from my understanding is that the condenser fan should definitely be on all the time if I have the ac on max for which it is not. I will take it to the mechanic in hope that they can find out why the condenser fan is not turning on.

[jamesmost]

The compressor run continuously when AC/defrost is on -----just it's internal displacement changes [automatically] by a factor of up to 10 based on the suction pressure [25-35 psi]........tries to maintain a narrow range of suction [low] pressure.................single wire on clutch [+12v] turns it on/off.

Now te HP required to turn compressor varies with its displacement, temp, and pressure. Obviously small drag in cooler temps/defrost vs 110F outside.

Not having a condenser fan operating [either relay or its motor failure [common with age]]...........will increase HP draw to turn compressor.

AT WHAT temp/intervals should the condensor fan engage. I have seen mine come on but not as often as i expected it to-[ As well i located a used compressor w/86k that was removed i week ago from an operating system, any thoughts on that)

[maxnix]

As well i located a used compressor w/86k that was removed i week ago from an operating system, any thoughts on that

If it was open for a week, probably not good for longevity of what life is left.

[DAEDALUS]

AT WHAT temp/intervals should the condensor fan engage. I have seen mine come on but not as often as i expected it to-[ As well i located a used compressor w/86k that was removed i week ago from an operating system, any thoughts on that)

The fan relays are activated if the water temp rises above 189-199*F or if the high side pressure rises to 206-220psi.

[jamesmost]

so what u r sa

If it was open for a week, probably not good for longevity of what life is left.

so inconclusion u think in 1 week the seals are shot new compressor is 5 bills / take out which may mr may not be halflifed 125, my mechanic did not advise a used one but said he would put it in

[elwesso]

Used AC compressors arent bad if theyre taken care of.. Either they need to be capped off so no moisture gets in or you flush them out real good with something to get all the old oil out...

If you leave that oil in there that will ruin things....

[ebraun]

I have a question about an A/C problem that I'm having with my 94 Q45 that is very similar to the initial question possed by rsiwicki. I am having a lot of the same symptoms with the A/C working some of the time and not at all in other instances, but my auxiliary fan is also not comming on when it should. It does work sometimes which makes me think that my problem might be my temperature and pressure switch. I do not want to pay someone to replace the expansion valve and find out that it wasn't the problem, because it is pretty expensive. If I have the dealership do a diagnostic test will it show if there is a problem with the expansion valve and the temp and pressure switch? My main problem is that I don't know if the expansion valve is sticking shut or if my switches aren't working proberly. Hopefully I'm on the correct path atleast.

[rsiwicki]

Unfortunately Friday Happy Hours are not beneficial to waking up 7am in the morning to take the car to the mechanic. I am planning to be good and skip happy hour this Friday so I can take it in on Saturday morning.

I will post what the mechanic says.

[rsiwicki]

okay....this is what the mechanic said.

the fan clutch is shot and needs replacing. The fan does spin fast, but not fast enough. You can literally take your finger and put it in the fan stopping it instantly and then it starts to slowly get back up to speed again although not fast enough. that explains why the AC only works when moving down the road or revving the engine while parked.

Another problem was the low pressure side was a little low so they put some dye into it and to come back later to find out where the leak is. He said usually the low pressure side leak means the evaporator. I am doing the fan myself and will take the wait and see approach before coughing up the monies to replace the evaporator.

[DAEDALUS]

You're sure the car was warm enough for the clutch to engage fully?

The pressure reading will not tell you anything about where the leak might be, or even if there is a leak. If the leak was big enough to affect the pressure reading immediately, all the fluid would have leaked out long ago. If the low side's low then there could be a blockage in either the evap or the expansion valve. Expansion valve is most likely.

[rsiwicki]

the car was at operating temp and idling in Miami heat this morning for several minutes so it should have been fully engaged (I would think) as when he held the fan the condensor fan would kick on about 20 secs afterwards.

I hope it is the fan that is causing the problem...if not well then I just replaced my cluth fan for no reason.

[jamesmost]

rob definitely replaced it for no reason whatevrny compressor was making loud noises when engaged sup w/dat

[rsiwicki]

okay....I just replaced my fan clutch for no immediate reason. The old one works just like the new fan clutch except that it turned a little smoother. This is starting to get a little old trouble shooting and replacing things that don't need replacement. Another $150 down the drain.....should have know better than to trust the mechanic. I had that feeling where you question his judgement in your head not saying anything as something does not seem right, but being the so-called "expert" that he is and me a novice....I proceeded to take his recommendation which ultimately just plain sucks now as I have better things to do with my time. The love for the car is passing by very fast.....especially since I have all but destroyed my original rearend as it makes the most awful sounding clunks putting the car into reverse or drive and then letting off and on the gas while cruising. There is too much slop between the input shaft and the output shafts and I have a newly built 4.08 sitting in my closet waiting to be installed, but have fears of being stranded after my last 4.08 blew up after only being installed 1 day. The 4.08 will be installed next week while at my parents so maybe with a little luck that will go better than this ac crap.

I am leaving for a 700mile (each way) trip to my parents house in N. Florida and hope the AC continues to work on the freeway without any problems. I know of a mechanic or two up there that hopefully will be able to trouble shoot the problem, but initial thoughts are that I am the same problem (compresor valve stuck) James has after I have spoken with him. In my frustration...I almost pushed the car off the 2nd floor of the condo's garage into the intercoastal waterway hoping my AC troubles would float away.

[elwesso]

okay....I just replaced my fan clutch for no immediate reason. The old one works just like the new fan clutch except that it turned a little smoother. This is starting to get a little old trouble shooting and replacing things that don't need replacement. Another $150 down the drain.....should have know better than to trust the mechanic. I had that feeling where you question his judgement in your head not saying anything as something does not seem right, but being the so-called "expert" that he is and me a novice....I proceeded to take his recommendation which ultimately just plain sucks now as I have better things to do with my time. The love for the car is passing by very fast.....especially since I have all but destroyed my original rearend as it makes the most awful sounding clunks putting the car into reverse or drive and then letting off and on the gas while cruising. There is too much slop between the input shaft and the output shafts and I have a newly built 4.08 sitting in my closet waiting to be installed, but have fears of being stranded after my last 4.08 blew up after only being installed 1 day. The 4.08 will be installed next week while at my parents so maybe with a little luck that will go better than this ac crap.

I am leaving for a 700mile (each way) trip to my parents house in N. Florida and hope the AC continues to work on the freeway without any problems. I know of a mechanic or two up there that hopefully will be able to trouble shoot the problem, but initial thoughts are that I am the same problem (compresor valve stuck) James has after I have spoken with him. In my frustration...I almost pushed the car off the 2nd floor of the condo's garage into the intercoastal waterway hoping my AC troubles would float away.

Sorry to hear. just remmeber theres this stupid kid up north who might come down and commit a crime if you did anything drastic.....

I dont know why you didnt just get a used one from one of our parts cars, i didnt think about mentioning it when you ceased my peaceful slumber, but you know how it is... HOnestly, i think it was a better waste of money (if such a thing exists) than on a compressor to find out that wasnt the problem.....

You will at one point or another waste a good share of money on the Q (and you already have rob, who am I to talk!!!!!)..

[jamesmost]

rob befor u push it off the parkingdeck PULL THE FN HEADERS FOR ME !!!( i will ask my bud how he hot wired the compressor, call u later)

[maxnix]

....I proceeded to take his recommendation which ultimately just plain sucks now as I have better things to do with my time.

Like Q45tech says, get it to a certified AC expert with all the tools and quit fooling around with a "mechanic."

Have a safe and fun trip. Got radar detector?

[rsiwicki]

Verdict is in as I took the car to a really good AC speciality shop at my parents house in Destin, FL.....I need a new AC compressor. The compressor is weak so that is why when it spins faster (higher rpm) the AC gets cooler which makes some logic I guess. The problem is they can't fix it today or tomorrow due to ordering the parts and then the hurricane approaching quickly so people need to prepare for the storm.

They wanted $1,100 in total to change out the compressor which included new dryer and expansion valve. They were charging $460 on a remanufactured unit for which I told them no thanks since Joe can sell me a new one for $512. My question is what all exactly needs to be done when changing an AC compressor and how much do you all think I should be charged for the job. I was thinking more like $900 would be reasonable to do the job, but I have really no idea.

Thanks again for your input.....

[DAEDALUS]

Drier is a must, but I question the need for an expansion valve. There's no overlap of labor in R&R, but there is an overlap in the evacuation/recharge. I wouldn't get the expansion valve done. That's probably where most of the cost is in the quote.Remans sell on ebay for around $200. I hope they're good quality, since I bought one. It's cosmetically pretty nice, but I won't know how well it works for another few months probably.I had Pep Boys change my compressor for about $500 out the door back in 2000. It lasted 5 years, so I can't complain.

[rsiwicki]

Daedalus.....that $500 at PepBoys was it labor only? or did it include the cost of a remanufactured compressor?

I will skip the expansion valve at $200 and hope that doing the compressor and drier is good enough.

[DAEDALUS]

The $500 was everything, except I declined a new drier. What can I say--at the time I just thought they were trying to upsell me on something I didn't need. Maybe if I had installed a new drier then instead of a couple years later the compressor would have lasted more than the 5 years.

[rsiwicki]

I finally got my AC repaired as it was not all that bad because it worked fine after running for 2~3 minutes but was not very dating friendly as the women would complain about it so now all is good and I can freeze her butt off now. I bought a slight used (5,000 miles) OEM compressor off of another NICO member (thanks a bunch) and had it intalled along with a new OEM drier and vacum/recharge. All is good as I now have very cold AC and it starts cooling immediately so all is nice and cool now.

Now I get to tackle my TCS actuator on my own this holiday weekend....oh the joy in getting the car running in tip-top condition versus spending a day at the beach.

btw....I decided to give a dude in his Mitsu EVO a big head on the way to the mechanic this morning and challenged him to a race while cruising at 70 mph on I-95 at 7:30am and no cars....knowing of course he would beat me as I could see an extra large intercooler under the car....we he pulled on me pretty good but I got his attention as he did not pull on me as hard as he thought he was going to as I was still within 1/2 car length of he rear bumper at 110mph and we got a pretty good even start against each other. You should have seen the ego trip this dude was getting for beating a 4,000lbs 10+ year old car.

Modified by rsiwicki at 4:00 PM 9/3/2005
Modified by rsiwicki at 4:01 PM 9/3/2005