c3 heater not working
10-22-2009, 09:31 AM
#21
Race Director
Member Since: Apr 1999
Location: CORVETTE 77 385 C.I. TEXAS
Posts: 11,520
Likes: 0
Received 12 Likes
on
12 Posts
Along these same lines, the HVAC system was not working on my '74, so I take the covers off around the heater control and notice that the coupler with all the vacuum lines attached is not hooked to the control "manifold". Normally I would think that it might have just slipped off after 35 years, but the bolt was still in the side of the control box.
I hooked it back up, and it seems to be working. Defrost works great, but vent and heat are not blowing very hard. The AC is another issue.
My questions are:
1) Is disconnecting the vacuum lines from the control a standard fix for some problem (like should I soon be expecting antifreeze to be coming out of the vents)? Based on the bolt still being in the control, it seems it had to be intentionally removed.
2) Is it an obvious problem when the defrost blows strong but the other outlets do not, or is it just chasing down vacuum lines and lubing doors?
Thanks.
I hooked it back up, and it seems to be working. Defrost works great, but vent and heat are not blowing very hard. The AC is another issue.
My questions are:
1) Is disconnecting the vacuum lines from the control a standard fix for some problem (like should I soon be expecting antifreeze to be coming out of the vents)? Based on the bolt still being in the control, it seems it had to be intentionally removed.
2) Is it an obvious problem when the defrost blows strong but the other outlets do not, or is it just chasing down vacuum lines and lubing doors?
Thanks.
I wrote this up awhile back for this problem.
The vac. switch itself is probably not switching due to vac. leak as the rivet is not holding the 2 main switch parts together well. Besides replacing, it is also possible to tighten this &/or lube w/ a thin layer of white lithium grease to fix.
So it sounds like the rivet broke & he put a bolt in. 2 nuts on the bolt to lock the position should help.
10-22-2009, 03:35 PM
#22
Racer
All these systems should have been checked out before you bought the car...especially since the car would be your main mode of transportation. The A/C-heater-vent system is a complex hodge-podge of parts that interrelate the vacuum, electrical, and mechanical parts of your car. It is not something that can be checked out simply...unless you are a specialist in that area. There is only one sure way to get this fixed: diagnose what works and what doesn't...then determine why it doesn't work correctly...then disassemble to repair those faults [and any other worn/old parts that make sense to fix while you are in there]. You might be able to "Band-Aid" a fix temporarily; but a 'permanent' solution is not likely to be found with a piece-meal repair effort.
As to Ganey's comments, the rivet between the two metal pieces is still there; the bolt was to hold the rubber piece with all the hoses to the control head assembly (like in the picture earlier in this thread). Since you and 71T did not recognize the detachment as a standard bubba fix, then I am going to assume it was a sloppy repair, and just monitor the situation. 454 cubes should be able to pull enough vacuum to cover a small leak.
Ganey, I will go back and review your prior posts as well. Thanks.
10-22-2009, 03:54 PM
#23
Team Owner
Glad the fix was that simple. Many times it is not. While in there, make sure you test all of the circuits (vacuum and electrical), the diverter door servos, and the seals to repair what is needed. It will save you time in the long run. 
