Engine/Transmission (1994 - 1998) Fan Switch

[CPH]

Guys,

I need some ideas. When I try to use the vent switch, it will not change from defrost and floor vent position. It dosen't matter if the AC is on or off. It's a drag not getting airflow through the dash vents. I don't have a manual. Are there any relays in the system or is it just the switch?



CPH

 

[drrhoades]

Check the vaccum lines around the fuel filter area. I knocked one of them off on accident and had the same problem as you. If those lines are alright go thru and check the rest of them. But I would start with the ones by the fuel filter.



Doug

 

[CPH]

DRHOADS,

Thanks, I'll take a look and see what I can find.



cph

 

[Andy Redmond]

Your vent door actuator is likely bad due to oil contamination.



Look at the one on the transmission hump, above and right of the accelerator pedal. I bet the lines have oil contamination and the acuator diaphram is stuck/leaking.



I have replied to lots of posts on this issue and repaired many trucks with the oil contaminated vacuum system.



Also see the dodgeram.org site for recalls and tsb's on this issue.



You can test it with a mighty vac hand vac pump to see if its working right.



Good luck

Andy

 

[CPH]

Andy,

I did'nt know contamination was a problem in a 97 year truck. is there a simple fix?



cph

 

[illflem]

CHP, contamination is just as much a problem in later years it's just that they aren't covered by recall since the brakes aren't vacuum boosted.

Recalls only cover safety problems.



Not sure which year if ever the check valve to correct the oil in vacuum line problem was introduced. That's all that is added in the recall as long as no contamination has occurred.



Details here http://dodgeram.info/tsb/1996/24-16-96.htm

 

[CPH]

So, If I have a contamination problem, I'm Sc#$% because my truck wasn't under the recall! Sounds fair to me!





cph

 

[CPH]

Andy,

Can you tell me where to look for the vaccum source? I looked under the dash and the hose elbow that connects to the servos looks clear( it is clear plastic) I have no oil showing on the servos or the clear elbows. It looks like the vaccum source is at the power steering pump. I am going to buy a mighty vac today. Any other sugestions? Do the vaccum lines attach to the back of the dash switch?





CPH

 

[Andy Redmond]

Vaccum source at is at the vacuum pump, which drives the ps pump on your truck, put your mightyvac or vac. gauge on the vacuum pump and start the truck. You should have 20-25 in of vac. at idle or rated rpm, if not your vac. pumps not putting out . .



You can remove the battery and battery mount to assure acid from a leaky battery hasn't eaten up the vac. servo for the cruise control.



You can disconnect a vacuum line on the firewall and look for oil contamination. .



The hvac control does have a vacuum cluster on the back side. .



The clear tubing will often not show signs of oil contamination (readily). You can attach the vac. pump/mighty vac and see if the actuator holds vacuum or moves smoothly as a vac. is applied or released.



Did I hit everything? You might go to the dealer ship and ask to copy 5-10 pages of diagnositics from the factory service manual.



call me w/ any questions you might have.



Andy

972-398-3934

 

[gitchesum]

https://www.turbodieselregister.com/forums/showthread.php?s=&threadid=65465&highlight=vents



You might also check this thread. I had the same problem. Luckily, there was no oil contamination, just a bad actuator.



There are links to some pictures of the actuator that controls the defrost to vent action.

 

[CPH]

Gitchesum,

Exactly what I was looking for! The thread describes the switch and the fact that it is a vaccum switch not electric. Once again, the membership comes to the rescue! Thanks again guys! I'll let you know how it all works out.



CPH

 

[CPH]

Andy,

Didn't mean to forget you. Your description plus what Gitchesum sent should do me fine to trouble shoot this problem. Thanks again.



CPH

 

[Andy Redmond]

Just go enjoy a good Bagel, when I lived in North Jersey for a few months after college, I got hooked!



I think your down on the Jersey shore though? Maybe some steamed clams or something like that then!



Good luck, Andy

 

[CPH]

Andy,

Your right. I'm at the southern tip of the state. right near Cape May. Got goood bagels down here too! My wife freezes them and sends them to her best friend in her home town of Batesville Ark. No place to get a real bagel there! Thanks again for the help. I'll be fixin' this thing this weekend.



CPH