AC not cold enough
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Mountain Pass
Joined: May 2004
Posts: 101
Likes: 0
From: GARLAND, TX
AC not cold enough
93 F250. Converted from R12 to R134a before I bought it. Last summer cooled down just fine. This year not cold enough. Will get as low as 50 degrees at the vent when running down road and RPMs up. But when sitting still, the temperature at the vent goes up to near 80 degrees.
I checked the charge. 55 psi. My next guess is the orifice tube.
What do you think? Any other ideas?
I checked the charge. 55 psi. My next guess is the orifice tube.
What do you think? Any other ideas?
Hotshot
Joined: Jan 2004
Posts: 19,767
Likes: 1,082
From: St Louis
Before replacing anything:
1) Check pressures using a manifold guage set. Report readings and ambient temps. Report center vent temp.
2) With engine idling and A/C on, spray the condensor with your garden hose for several minutes while watching your center vent temps. Let us know what happens.
Steve
1) Check pressures using a manifold guage set. Report readings and ambient temps. Report center vent temp.
2) With engine idling and A/C on, spray the condensor with your garden hose for several minutes while watching your center vent temps. Let us know what happens.
Steve
Thread Starter
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Mountain Pass
Joined: May 2004
Posts: 101
Likes: 0
From: GARLAND, TX
OK, had some time to play with the truck this afternoon.
Don't have a full AC manifold gauge set. I've just been using the fill hose & gauge combination to get readings at the low pressure fitting. I understand that this gauge may not be dead on accurate.
Current readings as follows:
At idle, low pressure reads 42 psi, temp at vent approx 70 degrees.
At 1200 rpm, pressure reads 28 psi, temp at vent approx 67 degrees.
Ambient temp in both cases, 85 degrees.
Compressor clutch constantly engaged. No cycling.
With continuous driving, not idling, temp at vent will get down to approx 52 degrees.
Tried running water thru condensor while truck idling. Compressor clutch would begin cycling, and temp at vent went up to about 75 degrees. After taking away water, temp at vent goes back to about 70 degrees, and compressor clutch quits cycling.
I'm stumped. Hope this helps someone figure this out. If not, I'll be buying a gauge set tomorrow. I assume the gauge set is most needed to get the high pressure readings.
Don't have a full AC manifold gauge set. I've just been using the fill hose & gauge combination to get readings at the low pressure fitting. I understand that this gauge may not be dead on accurate.
Current readings as follows:
At idle, low pressure reads 42 psi, temp at vent approx 70 degrees.
At 1200 rpm, pressure reads 28 psi, temp at vent approx 67 degrees.
Ambient temp in both cases, 85 degrees.
Compressor clutch constantly engaged. No cycling.
With continuous driving, not idling, temp at vent will get down to approx 52 degrees.
Tried running water thru condensor while truck idling. Compressor clutch would begin cycling, and temp at vent went up to about 75 degrees. After taking away water, temp at vent goes back to about 70 degrees, and compressor clutch quits cycling.
I'm stumped. Hope this helps someone figure this out. If not, I'll be buying a gauge set tomorrow. I assume the gauge set is most needed to get the high pressure readings.
Senior User
Joined: Jan 2002
Posts: 255
Likes: 0
From: "tween the cotton and tob
Sounds like a blend door problem. Blend door is hanging up and letting outside hot air in. With an idle, lowside pressure reading of 42, the vent temp should be alot cooler.
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Senior User
Joined: Sep 2003
Posts: 394
Likes: 0
Agreed, The heater over powers the AC 100:1.
Also the heater is after the AC in the airstream.
so a LITTLE bit of heated air will give you warm AC.
Temporarily clamp the heater hoses. And recheck.
Also the heater is after the AC in the airstream.
so a LITTLE bit of heated air will give you warm AC.
Temporarily clamp the heater hoses. And recheck.
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