gsimon767

Is there an adjustment for the temperature control cable from the controller in the console to the mixer door in the heater A/C plenum?

Today while driving the outside temperature was low 50s. With the heater control set to vent and the temp set to cold there is warm air coming out of vents. What needs to be done to adjust temp cable or to better close temperature mix door?

Car is a 75 with Air Conditioning. Just had AC system reinstalled. All A/C components in the engine side of firewall are rebuilt and working but air from vents doesn't get very cold. Suspect temp control door in plenum not closing all the way.

How can I troubleshoot this?

BLUE1972

Before you go crazy, check the engine compartment for open areas where heat and hot air from the fan can enter the A/C system.
Check the A/C mounting and seams around the engine side of the unit. Check where the pipes enter the unit both A/c and heat. You can seal with dum-dum.

If I remember right you can adjust the cable by loosing the cable holder at the heater box end and sliding the outer cable shield in or out.

derekderek

also has vacuum controlled water valve on heater hose. you could have stuck open valve or no vacuum to it. i dunno if vac pulls it open or closed. but disconnecting heater hoses to firewall and looping them together would be a quick test.

Big2Bird

On the 81 there is. Under the console right behind the lever is a place you can change the sheath length.

Jud Chapin

I went thru this with my '76. Have a look at the weatherstripping on the rear of your hood to be sure it's there and that it's sealing. That keeps hot engine compartment air from entering the duct work.

4SPDL81

Willcox has excellent drawings/diagrams of the heat and air for your specific model year car...Good Luck!

gsimon767

Thanks to all who replied. My weatherstrip at the rear of the hood is in good shape. I had the evaporator housing out of the car and re-sealed it after cleaning evaporator so I am confident it is not leaking. There is no heater water shut off valve on airconditioned 75s. Probably engineers left it off as there was less room because of compressor and exhaust crossover valve. I believe all 76-77 had heater shut off valve.

I suspect the temperature mix door is just not shutting all the way. I was hoping someone might have a picture showing where cable is adjusted.

cobrachuck

You are correct no hot h2o shut off. I have a 75 auto ac L48 car just restored. Go to the hardware store, get a 1/2'' ball valve install it between the engine & heater core manually close the valve for no heat, measure with a IR gun. Remove the handle put it in the glove box for later.
I lowered pass side foot well 30 degrees by doing this.
Chuck

7T1vette

Many times the seal on the right kickpanel door is shot....so that it won't seal off incoming (warm) air. If this is your problem, you can remove that door by pulling upward on the spring/pin at top of door.

You can buy a $1 sheet of black 'craft foam' (8x10" sheets) at a local craft store. Drill out rivets; cut seal LARGER than what's left of the old one; assemble with pop-rivets. Re-install door that will now seal!!