2nd Gen Non-Engine/Transmission AC gets warm at stop light

[Dave MacArthur]

I have the same problem. I'm convinced it is a fan clutch issue. Even if the fan clutch is working normally, you're getting enough cooling for the engine (doesn't really require any at idle) but not enough air flow to keep the A/C cool. They are two separate issues and should be designed as such. I bought a Horton fan but haven't installed it yet. The Horton has an A/C pressure switch to turn the fan on whenever the A/C is running.

 

[Duluth Diesel]

I think the compressors are not as efficient when being turned at idle. Both our vehicles blow warmer at idle. I have had my CTD parked idling on a very humid day last summer. I had the air on full blast, and after about 5 minutes ice chunks were falling on the concrete.

 

[stacerbob]

You answered your own question in the first post.

Drive around and get it hot, go home and park, see if it starts to get warm. Put a fan in front of it and see if the temp goes back down. Like a box fan on a table. If the compressor is not engaged when this is happening, check the pressure switch. The one screwed on the receiever/dryer.

 

[Matt42]

Fan Clutch

I would also check the OEM fan clutch. In many climates with light to moderate loads, the fan clutch may never engage, or when nbot engaged the viscous fluid filler (if it uses the stuff) may not "drag" enough to turn the fan with any useful enthusiasm.



Around here, once the weather got over 105F and stayed there (low of 91 overnight), I have forgotten what it's like to hear the fan clutch shut off.

 

[WDaniels]

Most of the time when the air gets warm from the vents at a stop is when there is no air movement through the evaporator and the head pressure in the compressor gets to high and the unit does not cool efficiently. When air is moving through the evaporator and cools the coolant, the head pressure drops and it operates more efficiently. That is why most if not all exhaust brakes have a pressure switch that screws into the return(I think it's the return) line. The pressure on the switch is 325 on and 235 off. When the pressure switch closes it starts the clutch fan, drawing a large amount of air through the evaporator cooling the r-134. The original installers of my exhaust brake left the switch off and when I stop my air conditioned air gets warm until I start moving again. Hope this helps.

WD

 

[Deezul1]

Interesting about the pressure switch for the exhaust brake. I havnt heard about this or seen reference to it in my BD brake instructions. Please tell me more, like what does it do and what is the purpose of the EX Brake being tied to the AC.

 

[athompson]

Re: Fan Clutch

Originally posted by Matt Shumaker

Around here, once the weather got over 105F and stayed there (low of 91 overnight), I have forgotten what it's like to hear the fan clutch shut off.

Amen to that. My A/C works so well that it will freeze me out even when it's 115 outside. But my fan clutch has been engaged since the end of May. I don't expect it to disengage until the end of October.

 

[WDaniels]

Deezul1,

First of all, let me clarify my last post because it was around 2 am or so when I wrote that and I must have had my head up my behinder regions. It isn't the exhaust brake, it is the after market clutch fans IE... horton and others. Do you still want to know about the pressure switch? Now that I have grabbed my right ear with my left hand and my left ear with my right hand and said "POP" thus pulling my head out! Sorry for the confusion.

WD

 

[Deezul1]

WDaniels

Thanks for the chuckle, now it all makes sense