1988 Chevy S-10 Vent Control Problem with '88 S10 Chevy Bla

jbil · Posted at Wed Jul 02, 2008 5:05 pm

Heater problem
1988 Chevy S-10 6 cyl Four Wheel Drive Automatic 160,00 miles
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The heater/AC on my '88 S10 Chevy Blazer blows hot/cold air well. However, when I adjust the selector to any of the AC choices, the air only blows on the floor rather than
the dash vents.

I've checked to see that the 2 vacuum hoses are connected to the heater/AC diaphragm on the floor. Maybe the other ends aren't connected.

Questions

1. Could this be the reason that the baffles don't adjust to bring the air to the dash vents?

2. If so, is there a diagram showing their location on the other side of the firewall?

3. Is there a handy "how to" cheat sheet to disassemble/reassemble the heating/AC system if it turns out that the diaphragm is bad?

My Chilton manual is lacking any information on how to troubleshoot this problem,

Thanks a million,

Jbil

Advertisment · Posted at Wed Jul 02, 2008 5:05 pm

SWilliams · Posted at Thu Jul 03, 2008 7:55 pm

Does it do the same thing if you select the defrost or dash vents while in heater mode? Do you hear any hissing from the control panel area while in A/C mode?

jbil · Posted at Fri Jul 04, 2008 1:58 am

SWilliams wrote:

Does it do the same thing if you select the defrost or dash vents while in heater mode? Do you hear any hissing from the control panel area while in A/C mode?

No hissing sound heard. And air blows to defrost and floor regardless of selection.

SWilliams · Posted at Fri Jul 04, 2008 12:14 pm

Ok, Open the hood and look for a vacuum line that runs back to the dash. Follow that line and see if it is split/cracked or disconnected. That line feeds the control panel. It goes to a T in the line that connects to the vacuum reservoir. That reservoir has a check valve in it that may have failed. Follow the other line off the reservoir back to the engine, it will connect to a port on the intake manifold. That is the same line that actuates the 4X4 as well. So check that mess of vacuum lines for a leak as well.

jbil · Posted at Mon Jul 07, 2008 5:40 am

SWilliams wrote:

Ok, Open the hood and look for a vacuum line that runs back to the dash. Follow that line and see if it is split/cracked or disconnected. That line feeds the control panel. It goes to a T in the line that connects to the vacuum reservoir. That reservoir has a check valve in it that may have failed. Follow the other line off the reservoir back to the engine, it will connect to a port on the intake manifold. That is the same line that actuates the 4X4 as well. So check that mess of vacuum lines for a leak as well.

Thanks for the tip. I'll be checking the line in the next couple days.