air goes warm at idle but only for the first few miles | Ford Explorer Forums - Serious Explorations

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air goes warm at idle but only for the first few miles


August 5, 2008
Reaction score
City, State
Imperial MO
Year, Model & Trim Level
94 XLT
OK heres a weird one for you. I have a new compressor and new oriface tube and new accumulator. When I charged my A/C I only used 1 can. I liquid charged it on the high side and then waited for it to stabilize. low and high side are the same psi (around 85) engine off. at idle psi is 40 on the low and 150 on the high. Compressor cycles normaly for a few minutes then stays on. This is only after 1 12oz can of 134a. 1500 rpm and it will cycle every 10 seconds and cold air. I'll add about anouther 2 ounces to the system. Compressor no longer cycles even at 1500 rpms but the air is cold and everything seems fine. Here is the part that has be totally baffeled. If I get in my Ex and just drive I have no problems until I get to a light or have to stop. The engine starts to shutter and you can feel and kinda hear the compressor loading. The air goes warm in the car. If I kick off the AC the shutter stops but obviously I shut off my ac which isn't good either if its 95 degrees out. After about 5 miles of driving the problem goes away. I can stop all I want and won't have any problems unless I shut the car off for a few minutes and the problem starts all over again. Yeah:thumbdwn:
I havent been able to get any pressure reading when this happens b/c it only happens when I driving. If the ex is just running with it in park the AC is fine.
The fan clutch seems to be just fine. any suggestion? Junk compressor? bad condenser?

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You aren't going to like my comment. You need to take this to an a/c shop and have someone experienced evac and charge this. You replaced the compressor and accumulator? Why? Did the old compressor come apart? Did you flush the entire system? How much oil did you put back in it? Did the new compressor come with oil? If so, how much? A complete system charge? If so, did you drain all the oil from the condensor and evaporator so you're not over charged with oil? Did you evac the system? If so, how long at how many inches of vacuum? So many variables here that we can't begin to help you at this point. But the single biggest reason to take this to a shop is your statement you charged through the high side port. Not sure how you did this, but that is incredibly dangerous. You are subjecting your can of Freon to high side pressures. That can can go BOOM.... Never EVER charge off the high side. Next, how much charge does your system take? I can promise you it's more than one 12 oz can of Freon. Do yourself a huge favor and take it to a tech before you are paying for another compressor.

Let me clairify. I charged Hi side with engine off. Liquid charge. This was the first can that I put in. Hi side charging with system on is more dangerous than changing a tire w/o the truck in park. Anyway, anything that I put in afterwards with engine running was low side. New compressor b/c the old one seized. Flushed everyting that could be flushed. Replaced tube, accumulator and condensor. flushed everthing else about 4 or 5 times. Put system back together. Didn't get around to doing the rest until now. Now thats its on the 90's all the time. I put about 8oz of PAG46 oil in the whole system. 4 in the compressor, 3 in the accumulator and 1 in the condensor. Vacuumed the system for about an hour. I can get it down to -26HG. It goes no lower. Thinking there is a leak but I let it sit overnight and the next morning its still -26HG. could be my guages. Vacuum pump was a good one. bought it when I replaced the A/C in my house, it could pull 30HG easy. I'll put 1 12oz can of Dupont Sulvia R134 in. Engine off. Let the system stabilize then start the car. Compressor cycles every 10 seconds or so with the car in idle. I'll add about 2 more oz on the low side compressor stops cycling at idle. pressure sits and holds around 40psi 85 outside temp never drops or rises until I take it to 1500 rpm then it will cycle again.
Do you think two much oil? Like I said it only seems to load within the first 10minutes of driving then the problem goes away. I don't think I have to much freon considering its only about 14oz.
Thanks for your help on this one. I asked a ford tech were my BIL works but he just suggested start replacing things until it goes away and start with the compressor, he's never heard of that kind of problem. sounds economical dosen't it:confused:

Glad to hear no attempt to charge through the high side. But as a "best practice", avoid ever doing that so you don't inadvertently forget to close the high side valve.

You could have WAY too much oil, or just about right. Many compressors come with a full system charge of oil in them. You need to find out what yours was. Call the tech line of the manufacturer. I bought a brand new Motorcraft that had oil in it. Four Seasons remans usually do...but not always. You need to know.

You are way undercharged. The charge on a Gen II is 30 oz of Freon. I don't recall what your charge is. But I know it's a lot more than 12-14 oz.

thank you, a logical explanation. Is there a way to drain the existing oil out of the compressor. I assume set it on end for a few hours. I figure start over with the oil part. how about the condenser, hard to drain? I flushed it too just for the heck of it, didn't get much. If it were undercharged wouldn't it cycle rather than load or would 2 much oil negate that? also do you happen to know what the pressure is where the high pressure cut off switch will shut everything down, I figured that if the pressures are 2 high then it will shut it down unless of course the switch is bad.

I do not know the high side cut off pressure...but it has to be way up there because I've seen 300 psi and still going. There are charts available that will tell you how much oil to replace per component replaced. The factory service manual tells you too I believe. But you are on the right track at this point. Drain and clean everything. I would even pull the evaporator and drain it if it were me. Start fresh so you know for sure where you're at with the charge and oil.

Clutch Gap?

Did you already check the clutch gap? I'm asking because I'd had warm air from vent when stop at light or on heavy traffic. And after a while... cool again. I don't know about high and low pressure - I didn't check and I'm not able to had an argue about it. But in my case, just took off one spacer and A/C works fine!


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I havent checked that! I've had the clutch off a couple of time but never noticed any spacers but it seems that they are inside the clutch past the splines. I'll check the gap on mine. I'll report if this works or what I needed to do to make it work. Thanks for the suggestion.

well to eliminate any issues an not having to start over I did both suggestions. I removed 1 of the spacers which brought the clutch spacing into spec. I was showing more than .75mm which is way to much. now I'm at .40mm. I also drained all of the oil out of the system and started over. 4 in the compressor, 3 in the accum. and 1 in the condenser. Overall I added about 29oz of 134 and Its blowing ice cold and doesn't seem to "load" like it used to. I actually got it to start to do what it did before were the compressor seemed like it was struggling (not nearly as much as before). I got my wife to put the truck in drive and hold the brake. (this is when the air used to go warm) well no longer, and the pressures measured 200 high and 38 low, 75 ambient outside. So its not really the compressor overloading the system, its the engine loading trying to maintain the load of the compressor. With a properly charged system and a fully engauged clutch, the air never goes warm when stopped at a light. :D

thanks to both of you!:salute:
I'm not really sure which was the true fix but I believe now both helped considerably. My 2 year old complains that he's cold now in my ex, before he always seemed to break a sweat sitting in the back.

My 2 year old complains that he's cold now in my ex, before he always seemed to break a sweat sitting in the back.

Glad to hear it. :thumbsup: