2nd Gen Non-Engine/Transmission AC works then stops working

[KKunz]

the AC on my 99 24v works when I first get going but after about an hour it stops the fan still runs, it just does not seam like there is any cold air coming out. Im not sure what is called but the tank that is located on the firewall right behind the turbo will get about 1/8 inch of frost on it even if its 100F out side

 

[B.G. Smith]

The tank is the accumulator. Your air conditioner is either low on refrigerant or has restricted air flow across the evaporator. (most likely low refrigerant)r It is icing up the fins of the evaporator so you get no cooling. bg

 

[KKunz]

I had the AC charged this summer. Is the evaporator the thing in front of the intercooler? I hit a deer last winter so im thinking that that there is not enough air flow?

 

[B.G. Smith]

The evaporator is inside the cab under the glove box , the condenser is the one in the front, If you hit a deer there could be a leak up there, air flow across the condenser would not cause freezup but would definitely reduce the capacity of the unit to cool the inside of the truck. bg

 

[Andy Redmond]

KKunz:



I grew up in Thermopolis. I miss WY.



The orifice tube might also cause the freeze up (if this is the case) its not serviceable as its placed in the high side/pressure line during assy on the 98-02 models. DC can supply you with a new line. A faulty low psi switch on the accumalator might also allow the compressor clutch to disengage (off) , until the freeze up you describe.



Before we jump to any conclusions, pressures from a set of manifold gauges would be helpful in the diagnosis of the system. Perhaps your a/c tech can look for any leaks as well (provided that you don't have the tools/wherewithall to diagnose it yourself).



Good luck

Andy

 

[KKunz]

last weekend I was working on the truck and the carpet under the glove box was damp so could the dampness be from the AC?

 

[B.G. Smith]

last weekend I was working on the truck and the carpet under the glove box was damp so could the dampness be from the AC?

Yes, the drain could be obstructed or it could just be a result of the icing up?? bg

 

[Andy Redmond]

My guess is yes.



The drain maybe plugged, but with the freeze up the extra moisture can overflow or blow back off the drain tube getting the floor wet. Most of us that had this issue sourced some tygon tubing (5/8) and a hose clamp and routed the drain (extended it) to prevent this problem or similiar fix. FYI the drain tube is a black tube that protrudes from the firewall below the accumalator.







Good luck

 

[KKunz]

what causes the evaporator to ice up should i go under the dash and take a look at the evaporator. I guess I see what the problem is but what caueses the evaporator to go bad.

 

[B.G. Smith]

what causes the evaporator to ice up should i go under the dash and take a look at the evaporator. I guess I see what the problem is but what caueses the evaporator to go bad.

Been out of town since FR. The evaporator failure is usually a leak, caused sometimes from external corrosion caused by debris (leaves, pine straw, etc. )buildup in the AC housing and sometimes from internal corrosion, since it's the coldest place in the system, if there is any moisture in the system that can't be handled by the dessicant in the accumulator it ends up in the evaporator and when mixed with refrigerant, it forms an acid which eats on the metal. You may not have a bad evaporator, need to have someone do a good leak check on the system, compressor seal, hoses, line connections can all cause problems. bg

 

[Dan_69GTX]

You have 2 different questions - an evap freezing up isn't the evaps problem. An evap leaking is a bad evap.



The freezing can be caused by several factors - any good a/c man can diagnose the system and tell you why. It could be:

wrong charge in the system,

Bad cycling switch,

"blow by" past the orifice (too much refrigerant getting past),

incorrect refrigerant,

some moron put selant in the system,

etc.

or a combination of problems.



Dan