2nd Gen Non-Engine/Transmission A/C stuck in Defrost Help!!!!

[JYaekel]

Today while driving down the interstate, my A/C went from blowing through the vents in the dash to blowing through the defrost passage ways by the windshield. The selector switch for the A/C does not make a difference no matter what setting it is on. The compressor is cycling on and off and the air does feel to be cool around the windshield.



This is one of the weirdest things I have seen happen on my truck... Any ideas as to what may be wrong????

 

[Deezul1]

Fill out a signature so we can help you better. What year is your truck?

Some years have a 7 year unlimited mileage warranty on the vacum related parts. This is primarily 96 and what happens is the vacum pump will pull oil from the power steering pump and it gets through out the vacum system and rots all kinds of stuff. The default position of the heating /AC system is to the defrost vents. If you have a low vacum problem so the various doors dont open/close correctly then it goes to Defrost vents. My 96 had almost everything in the vacum system replaced at no charge and it had a bunch of miles on it. It was doing the defrost vent thing.

I believe the recall # is 720. Its not really a recall just a extended warranty for the vacum system.

 

[BatMan01]

A/C stuck in Defrost Help!!

I am far from an expert so I may be way off base. The controls are a combination of electric and vacuum. It seems possible that a vacuum leak could cause your symptom.

 

[parcher]

BatMan01 is right, you have lost the vaccuum supply to the mode door, Defrost is default. Your CTD has very few vaccuum lines this should be easy to find. Follow the vaccuum line from the pump (near the power steering pump) to the firewall and beyond.

 

[gitchesum]

I shot a few pictures of what went out on my truck. The actuator in the picture controls the dash vents. It's held on with 2 phillips head screws and it attaches to the vent door. It was kind of a pain to get it of the vent door when I removed it.

Everything vacuum related works on my truck. It would control from defrost vents to floor vents, it just wouldn't come out of the vents.

I have no idea what the proper name for the part is, nor do I have any part numbers because mine is still broken.



Hope the pics help a little.



#ad


#ad


#ad

 

[JYaekel]

Sorry, I forgot to give the details on my truck. It is a 98 4x4 auto with about 130k on the clock.....

 

[jtwcummins]

All modern HVAC units default to defrost when any failure occurs. Had this happen and cost 145. 00 for dealer to fix. They removed the windshield and the top of the dash rather than removing the dash to get to HVAC.

 

[Cooker]

I'm with gitchesum. That actuator controls the vents.

 

[Bob Hart]

ac on defrost

Had same proplem turned out to be Batt acid had leaked on vac hose replaced hose and no more proplem

bob H

 

[AggieJustin]

Check the vacuum lines running along the firewall above the downpipe from the turbo. This happen to a friend of mine's truck. The line fell down against the downpipe and melted a hole in the line. Once you lose vacuum, it will default to the defroster.



We patched the line, tied it up out of the way and all was good.

 

[Xgunfighter]

Had the same problum. My vac hose had seperated from the fitting at the vac pump on the engine. Dealer ordered new hose under warrante. Good thing it was over 85$.

 

[y-knot]

I have a 97' that did the same thing. Once it was just a matter of reconecting the vacume line at the pump (left side front on engine). Twice the vacume motor (servo) went out, and it will defualt to defrost. Two get to it you must remove the trime under the steering wheel, abs trim, remove the metal dash reinforment bar. It is located left side of duct work, held in by 2 screews. The dodge part # is 4720279AB ACTUATOR71-C list price 41. 20 net 34. 35. Once you are two it it is a 3-4 min job, the part is just cheaply made and wears out.

 

[Andy Redmond]

may have the dreaded oil contamination. . which runs the diaphram in the actuator.



see my post earlier today to a gent who 'repaired" vacuum lines leaking oil.



Also see TSB's on vacuum lines contaminated by oil.



Let hope its the simple fixes aforementioned.



Later,



Andy

 

[zues]

I have a 1998 12 valve and the vacuum line under the battery had a pin-hole. Fixed the line for about 7. 00 and works great.

 

[scotmartin]

The Vacuum motors "moulators" are a know problem. But a $10 hand vacuum pump and connect it to each motor under the dash and see if they move, bet you find one that doesn't. This happened on my dad's 96. I wired the door open, so they could keep the AC on their face. It was the same problem that you can look at in a previous post that has pictures.



Scot

 

[JYaekel]

Problem found! It turned out to be a melted vac. line that came loose and touched the turbo. Easily fixed... ... ... .



Thanks for everyone's help...