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AC/heat blower problems

B

Beardo'

NAXJA Forum User
Location
South, MS
Hey guys, need some help. So just got this xj a few weeks ago, and the heat and ac only blows from the windshield defroster. It blows this way on all settings. Could it be the switch? everything seems to be plugged in including the vaccum line.

specs:
1990 cherokee 4.0 auto
 
It is probably a vacuum problem between the firewall and the switch. If it was a relay the blower wouldn't turn on. It it was a resistor problem you would only get high speed on all of the speed settings.
 
Line from intake was cut open and stopped up, I spliced it back together and cleared the stopage. The Hardlines from the firewall seem to be ok.

Started it up, now have good vaccum to the canister(behind bumper) but nothing out of canister. Could the canister be bad? or stopped up? Sorry I dont know much about these canisters
 
Yes mud, found lots of good info. I am going to try to test the canister tomorrow afternoon and see if its leaking. Might go ahead and relocate it in the process.

Sorry didn't realize how common this issue was.

Thanks for the help!
 
Glad you found the vacuum leak!
Hope you find the root of your problem soon...

Sorry for yankin' yer chain, I think this problem was brought up like 10 times in the last 2 weeks... Glad you looked around a bit...

AND WELCOME TO THE FORUMS, DAMMIT!!! :kissyou:
 
Yeah, common problem.

Default position is defroster when vacuum is low.

Relocating the vacuum reservoir from behind the bumper into the engine compartment--under the pressure bottle shelf on a Renix--eliminates four feet of problematic vacuum line.

Some of the reservoirs have a single port, some have two--my 90 had the smaller ball type with a single port, I replaced it with a larger capsule type, still single port.

If you have Command Trac--NP231 with 2wd/4hi/N/4lo--you will also have the vacuum disconnect front D30 CAD, and without adequate vacuum you won't have 4wd.
 
Got another canister from the JY and relocated it to the engine compartment(the old one was cracked). So now I have heat!

But now when i switch to normal the blower is still blowing but nothing is coming out of any vents. when i switch the panel to off i can hear a slight hissing coming from behind the dash, I will assume I have another leak. Just not sure I am brave enough to rip my dash out yet!

But the heat works and that is my main concern.

Thanks again guys for the help!
 
Yeah, still could be low vacuum--IF you have the NP231 with D30 CAD that whole vacuum sub-assembly should be checked.
 
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