HVAC defrost only, vacuum lines are fine. What else?
10-24-2015, 02:57 PM
#1
HVAC defrost only, vacuum lines are fine. What else? I had this same problem with my 95 LT1, in that case it was just one of the hoses being torn. Having the same issue with my 98 LS1 but everything is hooked up properly.
The HVAC line/ fitting going from the back of the intake manifold to the junction is fine along with all the lines splitting off from there.
Could a leak from the engine/ emissions lines cause the HVAC not to work properly? Everything I've poked and prodded looks good so far, idle doesn't change when touching any of the fittings/ hoses.
What else can I do? Thanks gents.
The HVAC line/ fitting going from the back of the intake manifold to the junction is fine along with all the lines splitting off from there.
Could a leak from the engine/ emissions lines cause the HVAC not to work properly? Everything I've poked and prodded looks good so far, idle doesn't change when touching any of the fittings/ hoses.
What else can I do? Thanks gents.
10-30-2015, 03:11 PM
#3
I did come across a couple diagrams in one thread, can't find it now though.
I'm going to go poke around some more and examine the check valve more closely. If it looks fine then I'll try using vacuum to help track the leak down as suggested by shoebox here:
http://shbox.com/1/4th_gen_tech2.html#HVAC_vacuum
I'm going to go poke around some more and examine the check valve more closely. If it looks fine then I'll try using vacuum to help track the leak down as suggested by shoebox here:
http://shbox.com/1/4th_gen_tech2.html#HVAC_vacuum
10-30-2015, 04:14 PM
#4
Upon further inspection the checkvalve appears to in good shape from the outside.
I pressure tested all HVAC related lines and they hold. (I disconnected the one from the back of the intake manifold to check that one).
The lines that go the brake booster are hooked up fine. I disconnected one with the engine idling out of curiosity, no change.
Going to pick up a new checkvalve and hope its the culprit, thats what it was on my '95 but that one was obviously cracked. Otherwise I don't know what else to check short of dropping the engine and going over every hose..
I pressure tested all HVAC related lines and they hold. (I disconnected the one from the back of the intake manifold to check that one).
The lines that go the brake booster are hooked up fine. I disconnected one with the engine idling out of curiosity, no change.
Going to pick up a new checkvalve and hope its the culprit, thats what it was on my '95 but that one was obviously cracked. Otherwise I don't know what else to check short of dropping the engine and going over every hose..
11-01-2015, 01:59 PM
#5
Update:
After playing around with all of the hoses the other day, I have heat coming out of my dashboard vents AFTER 30 sec to 3 minutes of the engine running
It comes out of the defroster as it did previously, then switches over randomly. Also the first time I drove the car after playing with the hoses, it was exhibiting signs of a vacuum leak with a high idle. I parked it for the night and this morning it ran perfectly with the HVAC behaving as described above.
(Haven't had a chance to get a new checkvalve).
After playing around with all of the hoses the other day, I have heat coming out of my dashboard vents AFTER 30 sec to 3 minutes of the engine running
It comes out of the defroster as it did previously, then switches over randomly. Also the first time I drove the car after playing with the hoses, it was exhibiting signs of a vacuum leak with a high idle. I parked it for the night and this morning it ran perfectly with the HVAC behaving as described above.
(Haven't had a chance to get a new checkvalve).
11-09-2015, 08:06 PM
#6
Same deal still, 75% of the time it'll come out of the dash vents after a minute. For the rest it doesn't bother, still trying to figure this out. Haven't had any more high idle issues, but it has to be related.
Intermittent issues suck
Intermittent issues suck