I have a 97 Expedition E/B with 130,000 miles and rear ac. I have owned the vehicle for 6 years and 90,000 miles. The ac has worked fine for most of this time but has gradually gotten worse over the last year. The system has never been recharged since I've owned it. I am looking for help isolating the problem and repairing it myself but am not sure how to proceed.
I will describe what I have found so far. The front ac blows moderately cool at best. The rear ac blows warmer and there is a loud hissing sound coming from the rear unit (possibly the rear expansion valve?). The hissing seems to have gotten louder in conjunction with the degradation in performance of the ac. This may be my imagination as I seem to always remember a slight hiss back there, but it does seem a lot more noticeable than it used to. The tubes going into the rear evaporator coil are very cold and sweaty. I would think this means that my system does not need a recharge, but am confused why the system is not blowing cold air. The compressor seems to cycle on and off approximately every 10 seconds. The rear actutor works fine.
Should I just recharge the sytem using the Walmart kit with low pressure gauge or is that asking for trouble?
It sounds like your system is low on refrigerent, which can cause a hissing or whistling noise at the metering orafice, but as ultramagdan said, you nee to put on a set of gauges to see for sure what is going on, then go from there.
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Bill, in state of WA.
64 F-250 Custom Cab
292, 4 spd
Dad bought it new when I was six
Thanks...I bought a $20 bottle of R134a that comes with a hose and gauge (very cheap gauge). It was a little on the low side (25psi) when I started and is now at about 45psi and blowing cold front and rear. The readings throughout the process were a bit crazy going as high as 65psi. I attribute that to the cheap gauge and refrigerant going both ways into and out of the system because when I would remove the gauge and reattach it, it would provide a reading that was more in the normal range. I ended up going very gradually and relying on a combination of the gauge readings, the feel of the air and a little bit of common sense.
Having gone through this whole process it would appear that it is quite difficult to overfill the system as so many warn against in this forum. The pressure in the can of refrigerant seems to equalize with the pressure in the system at about 45 psi and it was impossible to dump the whole can of refrigerant into the system once the system pressure got to the correct level. This may not be true in all cases, but it was in mine. While it may be possible to damage your system by overfilling it, I think you would have a hard time doing that with thos little aerosol cans.
If after adding refrigerent, the temp is ok now,, you have a leak somewhere in the system, will be just a matter of time until you will be having the same problem again.
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Bill, in state of WA.
64 F-250 Custom Cab
292, 4 spd
Dad bought it new when I was six
How's it going? I have the same exact problem man. Same truck too, '97 Expedition. HERE'S my thread that I started somtime last week. I took it to a shop and they added some stuff that they said should've fixed the leak I had. It was supposedly in the AC evaporator which is what's hissing in the back behind a panel. I checked it and they were ice cold and wet. They filled it up with freon and it worked, well at least for a week and a half anyway. I'm not sure but my air doesn't seem to be as cold and the hissing sound will start up briefly, which means there's no refrigerent running through the tubes. I might just take it to Midas and have them check it out and get it fixed. Local shops are somewhat cheaper but sometimes they don't know what the hell they're doing, and you end up spending more. The shop said it would be $600 to replace the AC assembly, and when I asked if they were sure that was the problem, they kinda of stood there and shrugged. Hope you get yours fixed buddy.
in a refrigeration system, a leak must repaired by soldering (in the case of a copper coil), as far as I know, automotive systems use aluminum which almost always needs replacing< or in the case of a hoze or compressor seal, it needs to be replaced. after 25 years in the commercial refrigeration trade, I have never used an additive to stop a leak.
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Bill, in state of WA.
64 F-250 Custom Cab
292, 4 spd
Dad bought it new when I was six
Ya, I assumed it wouldn't work, but I pressured the guy to do it free of charge since he had a stupid look on his face when I asked him what was wrong. The ride home from work tonight was alright, there was no hissing, but I could tell the cold was fading. Hopefully I'm wrong.
sorry to sidetrack, but I want to add refrigerant to my Expy for the first time, I know how cause I've done it to my Accord. But the dumb question of the day is, "where is the Low-Side Service port" located on a 99 Expedition. I've got the tools and the refrigerant.
the low side tap is on the suction line (the one that goes from the compressor to the evaporator). my question is why are you adding refrigerent? are you sure it is low? first I would put on a high and low side gauge and see what your pressures are with the system running. If it is indeed low on refrigerent, you need to find the leak. if both gauges read the same, your compressor is not pumping. also before testing, be sure that you have good air flow across your evap, and your condenser fan is running. these are things that I would check first before adding or removing refrigerent.
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Bill, in state of WA.
64 F-250 Custom Cab
292, 4 spd
Dad bought it new when I was six
thanks for the response, I'll check the other things first, it just hasn't blown cold air in a long time, so my first inclination would be low on refrig. but I'll check for leaks. Never paid much attention to it until this summer.
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. I've got the tools and the refrigerant.
