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Topic: Cab A/C stuck on defrost  (Read 313 times) previous topic - next topic
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Cab A/C stuck on defrost
When I turn on the A/C in the cab it will only blow air from the front window area. Anybody had this problem?
Dale from Downey 27’ 2012 RB,”Casa Verde”, 2000 Jeep Wrangler. Formerly1991 RB & 1990 Jeep Wrangler.
Re: Cab A/C stuck on defrost
Reply #1 –
When this happened in our Lazy Daze, the culprit was the vacuum line from the manfold to the vacuum accumulator.  Rodent damage.  When I replaced the vacuum line, the dash vents were restored.

Harold
2014 27 MB
Towd: Either the Jeep Wrangler or trailer containing the BMW R1200GS and 2 E-bicycles
Happy wife=Happy life
Re: Cab A/C stuck on defrost
Reply #2 –
Hi Dale,

Many posts about this, below is a link to a recent discussion. My reply #1 has a link for an earlier thread about this, and reply #7 describes what I purchased to do the repair.

I referenced the Companion article on this topic (not sure if that is available again) and the youtube video I used for some guidance on how to install the check valve and where to place the reservoir.

Cabin A/C, no air coming out of vents

I hope this helps. I was a relatively easy job for me (and I'm not a skilled mechanic-- unlike quite a few on here).

Jason
Jason

2003 Rear Bath
"Razor Crest"
Our first RV, purchased from the original owner 01/2022
Re: Cab A/C stuck on defrost
Reply #3 –
Dale,
Here's another good video on the fix.
jor

a/c vacuum
09 27' MB
10  Suby Forester
Re: Cab A/C stuck on defrost
Reply #4 –
Quote from: Blueox25  - 
When this happened in our Lazy Daze, the culprit was the vacuum line from the manfold to the vacuum accumulator.  Rodent damage.  When I replaced the vacuum line, the dash vents were restored.
Harold
.
Exact same thing happened to us - wasn't a fun nor cheap repair.  Seems those vacuum lines are a delicacy amongst the rodent class...
.

2006 24’ TK
570 watts solar, 300Ah lithium
SKP Lifetime member #105622
Land of Enchantment
Re: Cab A/C stuck on defrost
Reply #5 –
Thanks for all the help. I’m pretty sure I’ve got a grasp of what the problem is and how to remedy it. It looks as though the bypass valve and the vacuum canister are the culprits. Since the vacuum canister is buried deep in the engine it is necessary to abandon the old canister and add a new canister in a more accessible location. There are several very good videos on U-Tube that show exactly how to do this. Thanks again and be well, all.
Dale from Downey 27’ 2012 RB,”Casa Verde”, 2000 Jeep Wrangler. Formerly1991 RB & 1990 Jeep Wrangler.
 
Re: Cab A/C stuck on defrost
Reply #6 –
I did this repair on my rig today.   It was a 30 minute fix once I understood the issue and located all of the parts.  

This video was helpful to me (same one linked a couple of replies up). 

https://www.youtube.com/watch?v=-192lHUs8nY


Troubleshooting the issue consisted of checking for vacuum (with the engine running) in the engine compartment (behind the oil fill neck) and on top of the dash under the pop-off cover Ford provides to access the blend door actuators.   

Parts included:
A/C Vacuum Reservoir Tank & Bracket for Ford Econoline Van #YC2Z-19A566-AA
Motorcraft YG193 Vacuum Checking Switch
A very short length of 1/8" vacuum hose

I was able to re-use vacuum fittings from the existing setup and didn't need any extra.

Rich
2003 MB