Hey all! I recently put a new condenser in the Fleetwood, and had it charged at Chad's dealership. It still blows warm at idle, and cool, but not cold while moving down the road. Any ideas on what I should look at next?

Assuming the compressor is actually running, you're going to have to put gauges on it and go from there. Could be anything, really. Did the shop vacuum out the air and moisture as part of the repair?

With the car idling, turn on the AC, then pop the hood. Have a look at the compressor clutch, and see how long and how often it is cycling. If it is short bursts, then you are likely low on refrigerant. If it was full at the shop, then you may have a leak.

Yup, that's what confuses me. The shop vacuumed all the air out first (I believe they use nitrogen) and then filled it. The compressor runs constantly, so I know I don't have a leak any more. With the old condenser, the compressor would kick on and off rapidly if I was filling it with R-134 myself from the can, but once the can was empty, the compressor would stop all together. So I know it holds a good charge without leaks, which is why I'm not sure why it would blow warm still.

The compressor is not supposed to "run constantly". There is something wrong...

Gotta put gauges on it. At the very least, get a low pressure gauge on it and tell us what it reads with the A/C on and the car idling.

I forget, is that R12 or r134a? I think it's the '94s had 134a. And to my knowledge the compressor was suppose to run all the time while the A/C was running. All the GM cars that I've had and that blew cold had non-cycling compressors. I know other makes cycle their compressors, but I didn't think GM did.

Anyways, the system may be overcharged. Too much freon puts strain on the compressor like high blood pressure. And it can't blow cold efficiently. Either that's the case, or you have too much PAG oil in there so there's less room for compressible freon. Hence a less-than-cool result.

In any case, we need those gauge readings!

134 started in the B and D bodys in 94.

While early GM systems did not cycle, the 94 certainly is supposed to.

Oh, that's good to know...

Are the '94+ RWDs equipped with the r4 compressor, or that real long one like on the FWDs or on trucks?'

Cool, thanks for the help so far. My service manual and gauge are at my parents' house, next time I'm out there I'll pick them both up and get a reading.

The 94-96's are HR6's. Very similar the DA6's....

I did have problems with mine (note the compressor replaced 2x before I got the car) and debris plugged up the orifice. Find my thread on it, I put a lot of detail in what I had to do to flush it and get it working. But nutshell, it went overpressure when you revved up and didn't cool and did cool at idle. But was seeing >500 psi and popping the overpressure popoff too when I added more freon (yes, I know, read my post on it).

Too much freon is damaging. If it goes liquid back into the compressor, you get to buy a new one....

I flushed mine and it worked WONDERFUL after that.

Well, I tested the pressure tonight, at idle, I'm seeing 90 psi, and at higher rpm (2000, maybe 2500, kind of hard to tell in a garage just playing with the throttle) it dropped to 75 psi. Does this mean much?

Brian

The pressures should ALWAYS be measured at 2000 rpm and all windows/doors open. Revved up is proper. 90 on low side or high? Low side, too high, high side, too low. I would expect 150-250 depending on the temps AND humidity. 500 is the max, so seeing 300-450 is not uncommon in hot humid temps (95/95 or so).

My chart is at home, PM me if you don't hear from me or email me to have me find it and post it. I don't have a scanner handy, but I can post temps in the 80's or 70's (where it is here right now, you are probably cooler at night than us)

Well, you could do this....http://www.chevytalk.org/fusionbb/showtopic.php?tid/192489/post/new/#NEW (second to last post)

Well, you could do this....http://www.chevytalk.org/fusionbb/showtopic.php?tid/192489/post/new/#NEW (second to last post)

Hahaha, yeah, but then I'd have to pay people to be seen with me in the car!

I wouldn't believe it if there wasn't a picture that looks pretty legit! We just won't talk about the last car on that post.....

plz don't be southview chevy's fault....plz don't be southview chevy's fault..... :crossesfingers:

Well, I tested the pressure tonight, at idle, I'm seeing 90 psi, and at higher rpm (2000, maybe 2500, kind of hard to tell in a garage just playing with the throttle) it dropped to 75 psi. Does this mean much?

Brian

That sounds grossly overcharged. Like by 2 pounds. It would be helpful to know the high side pressure, if you have that capability. I use my scantool on my Fleetwood, since the PCM monitors high side pressure with a transducer.

What does the low side read if you turn off the A/C but leave the gauge on there?

Is that with compressor running or not? It WILL soar pretty high (and match high side pressure) when the compressor is not running, when running it will drop. The drop is function of the compressor pushing against the restriction just after the condenser. Then it goes to the inside of the car to to the exaporator, then to the accumulator to collect moisture and to ensure no liquid freon gets to the inlet of the compressor then it starts all over again. VERY simple system really. The restriction has a filter on it too. IF it is plugged, high side pressure will skyrocket and low side will be too low. So if pressures aren't right, and proper amount of freon is in there (in lbs to be safe), then look at the restriction and then the only thing really left is the compressor if it isn't working right and not compressing anymore.

IF it isn't dropping, and not over pressurized look for the restriction damaged (letting too much go through). It is in the high side line just as the lines come out of the condenser next to the battery. Mine was plugged up with metal debris from crappy mechanics replacing the compressor and not flushing the system properly. I posted on that mess a couple years ago.

He said it dropped when he revved the engine, indicating the compressor is doing SOMEthing. But that's why I asked him to check with the compressor off. If pressure spikes to 120+ then it's definitely overcharged. If it doesn't change much then it's a compressor issue most likely.

It also could be a missing or somehow opened up orifice, but I don't know if that's really common.

Well, it's a little cooler today, so at idle now, I'm seeing 75 psi, and when I up the RPM it drops to 60 psi. When I turn it off completely and the compressor is not running, it jumps to about 95, 100 psi. But the compressor runs constantly when the AC is on. Tom, I'll look up your thread tonight when I get home, I'm home for 20 minutes on my lunch break right now. Thanks for the help so far everyone!

Brian

Sounds overcharged to me.

With the compressor off, just stick something in the low side valve and discharge it for like 5-10 seconds, then put the gauge back on, turn the compressor on, and let it stabilize. You should hopefully see lower pressure and colder vent air. Keep bleeding off refrigerant and shoot for 30-45 (at 2000rpm). Should be much colder by then. If that wasn't it, no big deal...refrigerant is relatively cheap. I prefer to discharge when the compressor is off because I've found a TON of oil comes out when the system is running, for some reason.

So too much pressure and it won't cool properly? But I remember when I first tried to fill it myself, if the pressure was too low, it would cycle on and off rapidly, from about 60 down to around 45, and then it would shut off. The compressor would kick on again at about 60 psi and then run until about 45 or so. I have plenty of R-134 left, I'll try this this weekend. Thanks so far!

Brian

Two things:
First, the air was coldest right before it shutoff, right?

Second, either your gauge is wrong or your low pressure switch needs to be adjusted or replaced. 45-60 is off. It should be 25-45 or so. The difference between 45psi and 25psi is about 21°F, meaning if it's really shutting off at 45psi, you are giving up a theoretical 21°F in your vent temps.

I'd verify that your gauge is accurate, then consider adjusting the low pressure switch, assuming it's adjustable. If not, replace it.

So that's two problems, really. And the defective/maladjusted switch might explain the overcharging by the shop. They may have noticed cycling and added 134a until it stopped. Interesting.