AC Compressor Noisey
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Cross-Country
Joined: Feb 2004
Posts: 80
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From: South Dakota
AC Compressor Noisey
Hi,
I have a 2001 Expedition with about 74000 miles. It has rear AC and the 5.4 engine. 4x4 if it matters. The problem I noticed is when I come to a stop I can hear the AC compressor howling. It's not extreemly loud but loud enough to be noticable in the cab. If I rev the engine so it goes just above idle the noise goes away. I don't hear it while driving. The AC is cold enough to freeze me out of the truck yet!
Any ideas? Do I need compressor oil? Is the noise normal? Will I be buying a AC compressor soon?
Thanks,
Dan
I have a 2001 Expedition with about 74000 miles. It has rear AC and the 5.4 engine. 4x4 if it matters. The problem I noticed is when I come to a stop I can hear the AC compressor howling. It's not extreemly loud but loud enough to be noticable in the cab. If I rev the engine so it goes just above idle the noise goes away. I don't hear it while driving. The AC is cold enough to freeze me out of the truck yet!
Any ideas? Do I need compressor oil? Is the noise normal? Will I be buying a AC compressor soon?
Thanks,
Dan
Senior User
Joined: Jan 2003
Posts: 338
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From: Tucson
Two ideas, one the compressor is about to call it quits with a bad bearing, or two it is low on charge and alos low on oil. The reason I lean torwards the second is that you said the system is very cold. When the refrigerant gets low it actually makes the system run colder until it gets so so that the low pressure switch on the suction side starts cycling the compressor. If the register air is below 38 then the evaporator coil is running below freezing and will start to ice up in high humidity. Look at all the lines for oil residue as this will be an indication of where your leak is. If you do charge the system do not use any product with a leak stop added. Also 134A is uses Ester oil.
Dave
Dave
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Cross-Country
Joined: Feb 2004
Posts: 80
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From: South Dakota
I'd say it's below 38...I took it on vacation last week. When I'd stop for gas & start it backup I'd have frost blowing out of the vents. I assume this is from water getting a chance to condense inside there without the blower running. I think you may be onto something here!
I've actually got a R134A pressure gauge, I just haven't been able to find the low-side port. I was going to run a pressure test on it before I left for vacation. Before I posted this thread I read around on here today and found out where it is. I'll have to check into this tonight.
What pressure range should I expect to see?
I've actually got a R134A pressure gauge, I just haven't been able to find the low-side port. I was going to run a pressure test on it before I left for vacation. Before I posted this thread I read around on here today and found out where it is. I'll have to check into this tonight.
What pressure range should I expect to see?
Thread Starter
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Cross-Country
Joined: Feb 2004
Posts: 80
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From: South Dakota
Ok, I checked the pressure. It was around 45-48psi with the clutch engaged. When I turned off the AC it went up around 55-60psi. This seems a little high. Could my compressor be making the noise because the system is over-filled?
