Heater and A/c System Help
Thread Starter
Intermediate
Joined: Jul 2006
Posts: 35
Likes: 0
From: Blacksburg Virginia
Heater and A/c System Help
Hey Guys-
I've read tons of threads on these items and couldn't find a specific answer to the questions I was wondering about.
My 77 AC doesnt work at all and the heat barely works. When I use the fan speed and location selection switch in the cabin, I only get defrost and one fan speed. Is my interior fan bad? Bad switch? Why wont my air redirect from defrost to other places? Bad switch or a vacuum problem? What are the common fixes/upgrades for this system?
On the AC, I'm going to isolate my heater core with a 1" and 3/4" PEX ball valve this weekend. I know my compressor isn't coming on. Do I need to replace it or could there be another reason it wont switch on? (Low system pressure maybe) If I replace the compressor what else should I upgrade or replace while I'm at it?
Thanks and sorry for all the questions, I've never worked with an AC system and I'm totally dumb to it. I've read the tech article on the archives and have a basic understanding now but sure could use some more guidance.
Thanks
Josh
I've read tons of threads on these items and couldn't find a specific answer to the questions I was wondering about.
My 77 AC doesnt work at all and the heat barely works. When I use the fan speed and location selection switch in the cabin, I only get defrost and one fan speed. Is my interior fan bad? Bad switch? Why wont my air redirect from defrost to other places? Bad switch or a vacuum problem? What are the common fixes/upgrades for this system?
On the AC, I'm going to isolate my heater core with a 1" and 3/4" PEX ball valve this weekend. I know my compressor isn't coming on. Do I need to replace it or could there be another reason it wont switch on? (Low system pressure maybe) If I replace the compressor what else should I upgrade or replace while I'm at it?
Thanks and sorry for all the questions, I've never worked with an AC system and I'm totally dumb to it. I've read the tech article on the archives and have a basic understanding now but sure could use some more guidance.
Thanks
Josh
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
"one fan speed"
The blower has 2 sources of power, low runs full time & the normal fuse for the other speeds. Check fuse.
"air redirect"
Vents
I wrote this up awhile back for this problem.
On at least later C3 the problem is that heater is the default position (no vac. or vac. leak) due to being designed in the north. Vent should be default. Very safe bet the problem is 1 OR 2:
1) The vac. line from engine may be damaged from heat - a small black plastic tube that goes in below the hood alarm switch into wiper valley. Replacing most of engine side w/ hose will fix. OR
2) The vac. switch itself is not switching due to vac. leak as the usually plastic 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.
3) If you have a heater, the small vac. tube to heater hose valve underhood may be damaged from heat & need replacing. Block w/o heater.
PS The design problem comment is not intended to be offensive to any of our northern friends.
The blower has 2 sources of power, low runs full time & the normal fuse for the other speeds. Check fuse.
"air redirect"
Vents
I wrote this up awhile back for this problem.
On at least later C3 the problem is that heater is the default position (no vac. or vac. leak) due to being designed in the north. Vent should be default. Very safe bet the problem is 1 OR 2:
1) The vac. line from engine may be damaged from heat - a small black plastic tube that goes in below the hood alarm switch into wiper valley. Replacing most of engine side w/ hose will fix. OR
2) The vac. switch itself is not switching due to vac. leak as the usually plastic 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.
3) If you have a heater, the small vac. tube to heater hose valve underhood may be damaged from heat & need replacing. Block w/o heater.
PS The design problem comment is not intended to be offensive to any of our northern friends.
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
...
On the AC, I'm going to isolate my heater core with a 1" and 3/4" PEX ball valve this weekend. I know my compressor isn't coming on. Do I need to replace it or could there be another reason it wont switch on? (Low system pressure maybe) If I replace the compressor what else should I upgrade or replace while I'm at it?
Thanks
Josh
On the AC, I'm going to isolate my heater core with a 1" and 3/4" PEX ball valve this weekend. I know my compressor isn't coming on. Do I need to replace it or could there be another reason it wont switch on? (Low system pressure maybe) If I replace the compressor what else should I upgrade or replace while I'm at it?
Thanks
Josh
If you go to R134, I would use a smaller orifice tube like the Ford Red .062 in place of the GM White .072.
