AC/Heat issue
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Joined: Apr 2006
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AC/Heat issue
The AC in my 91 F150 is ice cold.....for awhile. Then I get warm musty air then after lowering the fan speed ice cold again. Then I can crank it up again. If I play with the settings it'll get cold again.I don't know if it's related but I at best have warm air when the heat is engaged. Both heater hoses are hot to the touch so the heat should be blowing me out. Not a prob now but New England winters are not be kind. Are these two issues somehow connected?
Thanks to all for your previous help on various issues........leaf spring hangers are no fun........ha ha!
Thanks to all for your previous help on various issues........leaf spring hangers are no fun........ha ha!
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Joined: Feb 2004
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From: Kansas City
Heat first, have you checked the coolant level in the radiator? If the level is low enough, it won't send hot water to the heater coil.
If thats okay you may need to check the flaps and vent doors, and all the vacuum lines for for them.
AC
Is this all while you're sitting still, or driving. Highway or city?
Since these trucks have mechanical radiator fans, (which also cool the AC condensor) the AC doesn't work as well when your sitting still, because the fan isn't turning fast enough at idle. Mine will jump about 15 degrees at a long stoplight. (from 45 to 60 measured with thermometer stuck into the vent.)
You could be a little low on refrigerant. The system will shut itself off when the pressure is low. A normal sign of this is the compressor coming on for about a second and switching off, every 15-30 seconds. When it's really low, it won't even come on.
The inside blower fan is electric, so I don't see how that could affect the doors, unless one is just broken loose, then the fan could suck/blow it shut. possible.
What temp air comes out of the defroster?
If thats okay you may need to check the flaps and vent doors, and all the vacuum lines for for them.
AC
Is this all while you're sitting still, or driving. Highway or city?
Since these trucks have mechanical radiator fans, (which also cool the AC condensor) the AC doesn't work as well when your sitting still, because the fan isn't turning fast enough at idle. Mine will jump about 15 degrees at a long stoplight. (from 45 to 60 measured with thermometer stuck into the vent.)
You could be a little low on refrigerant. The system will shut itself off when the pressure is low. A normal sign of this is the compressor coming on for about a second and switching off, every 15-30 seconds. When it's really low, it won't even come on.
The inside blower fan is electric, so I don't see how that could affect the doors, unless one is just broken loose, then the fan could suck/blow it shut. possible.
What temp air comes out of the defroster?
Last edited by clstrfbc; Jul 30, 2006 at 05:19 PM.
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The coolant level is good. As far as flaps, vent doors and vacuum lines, it sounds like a good place to start. If I only knew where to look.
AC. I actually noticed this happening during highway driving. It was a stop and go for a bit. After reading your reply I went out and got a thermostat to stick in the vent. Tomorrow I will check on the compressor regarding low refrigerent(Good idea!) With outside temps in the upper 90's for the rest of the week I'll do some research and post my findings. Many thanks!
AC. I actually noticed this happening during highway driving. It was a stop and go for a bit. After reading your reply I went out and got a thermostat to stick in the vent. Tomorrow I will check on the compressor regarding low refrigerent(Good idea!) With outside temps in the upper 90's for the rest of the week I'll do some research and post my findings. Many thanks!
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Joined: Sep 2002
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From: Philly Area, PA
I have the same problem with my A/C. It'll run for maybe 5 minutes just after starting with no problems, but then the compressor won't run anymore. If I switch the fan speed it will sometimes kick back on, but the compressor will usually only run for 15-30 seconds, then its off again.
My guess is that I'm low on R-12 and the pressure switch is turning the whole thing off. There's enough refrigerant in the system that after sitting for a while it works ok, but then there's enough that's liquid and not a vapor that the pressure drops off and turns the system off. I'll be taking it to a shop for a professional diagnosis in a day or two. I'll check back in then.
My guess is that I'm low on R-12 and the pressure switch is turning the whole thing off. There's enough refrigerant in the system that after sitting for a while it works ok, but then there's enough that's liquid and not a vapor that the pressure drops off and turns the system off. I'll be taking it to a shop for a professional diagnosis in a day or two. I'll check back in then.
Senior User
Joined: Feb 2004
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From: Kansas City
Yes, once you use what's in the accumulator, then the pressure gets low, and off it goes.
How blower fan speed affects, I'm not quite sure. But, I believe you.
The shorter it runs, the lower you are. 15-30 seconds might only need one can, maybe 2.... not running at all probably 3.
How blower fan speed affects, I'm not quite sure. But, I believe you.
The shorter it runs, the lower you are. 15-30 seconds might only need one can, maybe 2.... not running at all probably 3.
Freshman User
Joined: Sep 2002
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From: Philly Area, PA
Had a shop do the A/C repairs. They changed over to 134a, changed out the drier. Then they found that my compressor couldn't handle a full load of refrigerant - at idle there was effectively no A/C. So then they did the compressor. Quite an expensive repair.
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Joined: Apr 2006
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Ok folks here we go. On the hottest day of the year I drive home noticing the temp gauge is about halfway. Upon arriving home the overflow tank is actually boiling. Left the truck sit. Today I drained the coolant ( or what was left of it), flushed as per the prestone kit. When I put the heat on it was actually cool. It had been running for a while. Heat should've blown me out of the cab. Temp gauge read normal but I could'nt touch the water coming out. HOT. Also nothing came out of the drain plug? I notice when I go to put the defrost on the AC compressor kicks on. I also noticed the AC canister and all the lines associated with it are all cold? Changed the thermostat too. Please tell me the spring goes toward the block. Doesn't matter it leaked anyway got to take it out. Any ideas?
Thanks!
Thanks!
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