AC is a bit weak. First step in rehabilitation?

[Jesda]

Last year my AC was powerful, but now it seems to take forever to get cold and even then feels weak. The compressor, drier, expansion valve, and amplifier/controller were replaced in 1995 at the dealer.

I assumed the pressure switch was okay because the compressor engages and cycles normally.

What should my first step be in improving performance? A flush? I suppose a flush would also tell me if it was low on refrigerant?

[elwesso]

The compressor should NOT CYCLE unless its really cold outside. THe compressor should stay on ALL the time unless you put it on econ.

Whatsthe service history on the AC system? if memory serves there was a bunch of AC work done?

I would just go to a shop and have them hook it up to a gauge set, that will tell all!

[Jesda]

I went outside and checked it out (75F at the moment). I guess the compressor is staying on (middle part still spinning), but I hear an occasional click, the same click as when you turn the compressor off and on.

Is that normal? I thought the pressure switch was supposed to cycle the compressor to maintain correct pressure, or is the pressure switch just there to kick for protection when refrigerant is low?

Much thanks.

[elwesso]

When it clicks is the compressor clicking off and the middle part stops spinning? I would have to assume the compressor is turning off because I cant think of anything else that would cause that noise. Does the cooling fan ever come on (electric one in front of the condensor)? Maybe the relay is tripping but the fan wont come on for whatever reason?

Most cars have this setup (the compressor cycles on and off) however the Q45 compressor is a variable displacement compressor. In other words, when pressure gets to a certain level, instead of the compressor turning off/on (like most vehicles) the compressor on the Q simply doesnt work as hard... Thats about as simple as I cna put it, theres mechanisms inside the compressor that cause the compressor to not "compress" as much once you dont need full duty cooling.

[Jesda]

AH! I'm glad you mentioned the condensor fan. It does not appear to be coming on at all. I checked the relay by swapping it with the injector relay.

I'll let the dealer figure out the rest. At least I don't have to worry about buying more R12. w00t!!!

[Q45tech]

Just ordered 180 pounds of R12 to service our [Lexus/Nissan] customers this summer. Enough to deal with 150 cars..............as not all will be 100% empty.

Our cost about $30 per pound in that quantity. If one waits until June the price doubles and falls again in winter.

We usually buy half a dozen junker Q over the year and that adds ~~10# to stock.

Unlike some shops which will recharge a slow leak system [for enough money] we follow the law and require repairs and zero measurable leaks before recharging.

We could sell 10 times the amount of R12 if we would just recharge the leakers for $150-$200 in July.

[Jesda]

It seems to cool best when coming to a stop, something that happened last time (on previous Q) when I had low refrigerant. Regardless, I will not be doing it myself this time.

[elwesso]

What is the service history on the AC?

[Jesda]

1995:The compressor, drier, expansion valve, and amplifier/controller were replaced by the dealer in Los Angeles. Thats it other than belts here and there.

This winter was the car's first time (ever, ever ever) being parked outside in cold weather, so perhaps the R12 hoses are now leaking.

[elwesso]

ok, so the system has been gone over at least once.... ITs sorta up to you at this point, id either do 2 things: Hook the guages up and see what happens, or just recharge it and hope.... Im leaning toward the former.

After driving for a while, does the service port on the firewall ever frost over big time?

[qship96]

1995 was a long,long time ago-any components replaced then are now just old used parts ready for replacment again

[Q45tech]

A 10 year old [150k+] compressor is like a 10 year old outside cat with all parts intact...................tired from fighting.

[qship96]

agree,my 188,000 mile compressor works,but not that efficient at idle or low rpm-- better at highway speed-even after a evac/recharge.... does this sound like a tired compressor?

[Jesda]

ok, so the system has been gone over at least once.... ITs sorta up to you at this point, id either do 2 things: Hook the guages up and see what happens, or just recharge it and hope.... Im leaning toward the former.

After driving for a while, does the service port on the firewall ever frost over big time?

It doesnt appear to frost over, but it seems to want to? It feels much colder than the rest of the metal bits under the hood.

OH, and in a surprise today, I opened up the caps on the service valves to find that they were for R134! The service records from 8/2/95 (57,000 miles) say "Freon-Recycled" but doesn't specify if its R12 or R134. The compressor installed was 92600-64U01. I tried to look up the part number but got no results.

Its just amazing when I comb through the records and see how many major components had to be replaced in the first five years. This Q45 was pretty awful.

[elwesso]

IF there isnt frost accumulating on the low side service port after a while of highway driving then its probably OK. Mine usually does it after about 15 mins of straight highway driving, but doesnt do it when putting around the city.

[Q45tech]

One looks at the exact low/high pressures vs ambient vs rpm to determine the status of a compressor...................oh and the sound level and signature at idle in gear when it's 90F outside..................quiet as a mouse or chuck chuckle, clang, chuck, chuckle, clang or 100 possible sounds inbetween.

[Jesda]

I was wrong. They were indeed R12 fittings. I forgot that when I did my last Q, I switched the fittings to R134 so I could use the R134 hoses.

I picked up a can of Freeze 12 at a small auto shop in town, and by some miracle Autozone had an R12 filling hose in stock. I didn't ask for it, worried that they'd request certification, so I just walked in the back, pulled it off the shelf, and took it to the register.

My AC is ice freaking cold now.