AC only blows down to 50˚ ... need expert

I'm having AC tech problems ...

Six months ago I had a new AC condensor with new AC lines installed. Before the installation, the compressor was making a rattling noise at idle ... with that typical whine that early XJ's seem to have---the tech claimed nothing was wrong with the compressor ... and proceeded with the R12 charge, etc. etc.

The cooling performance was very good ... better than before, I was happy.

But then, right after this AC service ... the compressor started making a random howling noise, at or above idle... sounded like and 18 wheeler coming to a stop.

I took it back to the dealer last week ... they told me the compressor was going bad. I said okay ... fix it. They had to order the part ... I took it in for installation this week and told the service writer: Now, it's gonna cool the same as it does right now, correct? He said: Oh yea, sure it will ...

So now that it doesn't cool like it did ... what could be the problem? The tech wrote: "May have a leak. Dropped 1/2" in 30 mins. May be R12 machine."

see my recent post for details:
http://www.naxja.org/forum/showpost.php?p=235304&postcount=15

Thanks for your help.

Bob

if the compressor was coming apart inside, the expansion valve is probably clogged from the internal pieces if compressor flowing through the system. the technician should have recommended that when replacing the compressor. there is also a possibility the dryer is contaminated. i have also seen other problems from compressors coming apart like the condensor getting stopped up. in the past i have fixed this by spraying a brake cleaner in the condensor and back flushing it with compressed air. lots of metal came out, so i blew out all the lines thoroughly, put a good vacuum on the system and charged it up. everyhing came out fine.

jneary said:

if the compressor was coming apart inside, the expansion valve is probably clogged from the internal pieces if compressor flowing through the system. the technician should have recommended that when replacing the compressor. there is also a possibility the dryer is contaminated. i have also seen other problems from compressors coming apart like the condensor getting stopped up. in the past i have fixed this by spraying a brake cleaner in the condensor and back flushing it with compressed air. lots of metal came out, so i blew out all the lines thoroughly, put a good vacuum on the system and charged it up. everyhing came out fine.

Click to expand...

Thanks for the input ... I looked in my service manual and the specs indicate the temp should be approximately 45˚ at 80˚ ambient temperature after 5 minutes of operation---that's on "MAX" AC and blower set on high. It also indicates "that high ambient temperature and humidity conditions will cause higher pressures and temperature conditions. If the clutch cycles, take readings before clutch disengages".

Well, it's been very humid around here this week ... so maybe the tech views 50˚ within the "normal" operating range. It does blow between 38˚ to 42˚ at night or early in the morning---but that's not when I need the AC.

Again, thanks.

i have a little trade secret that applies to 87-90 xj's and possibly 91's. in the heater/evap case under the dash on the passenger side, there is a little probe that senses evap temperatures. some are adjustable and some arent. if there is a small black sensor that looks like it is sticking to the case just behind the knee bolster its not adjustable. if is a metal one it is. if so there are 2 tiny screw holes. you can turn the screws inside and can get colder temps. one adjustment allows for longer compressor cycles and i cant remember exactly what the other does, maybe just colder temp allowance. but by turning them slightly as labeled on the sensor it may help. be careful not to go too far or it can cause the system to freeze up. just a little at a time and see your results. just a little stealership tip. good luck!

jneary said:

i have a little trade secret that applies to 87-90 xj's and possibly 91's. in the heater/evap case under the dash on the passenger side, there is a little probe that senses evap temperatures. some are adjustable and some arent. if there is a small black sensor that looks like it is sticking to the case just behind the knee bolster its not adjustable. just a little stealership tip. good luck!

Click to expand...

Thanks for the tip... unfortunately mine is a "small black sensor". The FSM does indicate in the performance diagnosis table there's an adjustable thermostat---should have bought a '90.

Something I noticed in the FSM ... if the compressor is overfilled with oil, it indicates that excessive amounts of oil in the system will hinder compressor operation and reduce cooling capacity. I wonder if they used the proper procedure when replacing my compressor ... it says they are supposed to fill the new compressor with the same amount of oil drained from the old compressor, plus 1 additional fluid ounce.

May be the reason for the diminished cooling.

How should I approach them and confirm they used the correct procedure ... without insulting the tech ?

Thanks.

are you willing to sacrifice the techs feelings for the money you spent to have your a/c repaired properly. go back and get what you paid for.

jneary said:

are you willing to sacrifice the techs feelings for the money you spent to have your a/c repaired properly. go back and get what you paid for.

Click to expand...

I called the service writer today ... I'm having a conference call with the AC technician on Monday. I wonder if it takes awhile to break in these compressors ... today it was 92˚ and the AC managed to get down to 40˚ ... it took a long time and a lot of driving to get there though. It seems it has the ability to get cool, it just takes too long.

Thanks.

if it was blowing cold before the compressor was replaced, there probably is some blockage, insist on clearing out the lines of any pieces of compressor that could clog the system. i still think the expansion valve should be replaced any time a compressor is replaced for that reason.

I took it back to the dealer last week ... they told me the compressor was going bad. I said okay ... fix it. They had to order the part ... I took it in for installation this week and told the service writer: Now, it's gonna cool the same as it does right now, correct? He said: Oh yea, sure it will ...

a properly operating r12 system should get close to 32 degrees.i've seen them a little higher and even lower than that.
keep that repair shop honest.