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No heat question

Reply #15 –
Should not have to remove the dash but will have to stand on your head.
The "crank handle" on the blend door shaft operates the blend door.
It is spring loaded to go to the cold setting. The air bypasses the heater core.
The "crank handle" should be plugged into a clip attached to a cable that the temp control operates.
More pics in post #8 of this thread.

No heat question

Reply #16 –
Quote from: TurboCoupe50;458292
... With properly operating components, burping a heater core should not be necessary...

New Radiator .. New Water Pump.
Both Heaters Hoses are HOT @ operating Temps.

--- So, Problem Must Be Behind the Dashboard


THANKS !! !!

No heat question

Reply #17 –
Quote from: softtouch;458303
Should not have to remove the dash but will have to stand on your head.
The "crank handle" on the blend door shaft operates the blend door.
It is spring loaded to go to the cold setting. The air bypasses the heater core.
The "crank handle" should be plugged into a clip attached to a cable that the temp control operates.
More pics in post #8 of this thread.

Thanks!  Guess one of will get to play contortionist this weekend!  Wish us luck!
1986 Mercury Cougar XR-7 Turbo-charged 5-speed.
Owned 22 years.

No heat question

Reply #18 –
Take out the 4 screws and pull the temp control out of the dash to get to the top end of the cable.
See the 3rd pic in post #8

No heat question

Reply #19 –
Quote from: softtouch;458309
Take out the 4 screws and pull the temp control out of the dash to get to the top end of the cable.
See the 3rd pic in post #8

Got it!!!
1986 Mercury Cougar XR-7 Turbo-charged 5-speed.
Owned 22 years.

No heat question

Reply #20 –
Quote from: softtouch;458309
Take out the 4 screws and pull the temp control out of the dash to get to the top end of the cable.
See the 3rd pic in post #8


Did that, this afternoon, and no new results

No heat question

Reply #21 –
Just a quick note, when replacing the thermostat I drill a 1/8" hole at the top of the housing so that air can continuously burp out of the system.  Been doing this for years on my Fords and never have a problem with air in the coolant system.  When both of the heater core hoses are hot this means coolant is circulating through the heater core and the issue is inside the cabin of the car.

83 351W TKO'd T-Bird on the bottle


93 331 Mustang Coupe - 368 rwhp

No heat question

Reply #22 –
Quote from: Aerocoupe;458331
Just a quick note, when replacing the thermostat I drill a 1/8" hole at the top of the housing so that air can continuously burp out of the system.  Been doing this for years on my Fords and never have a problem with air in the coolant system.  When both of the heater core hoses are hot this means coolant is circulating through the heater core and the issue is inside the cabin of the car.

Thanks for the advice!!!  We're thinking now that it's got to pretty much be something under the dash, either mechanical or a vacuum line.  Husband is working on getting up his nerve to pull the dash apart again (last time was to replace the heater core and he did NOT have a good time :(
1986 Mercury Cougar XR-7 Turbo-charged 5-speed.
Owned 22 years.

No heat question

Reply #23 –
Quote from: Aerocoupe;458331
"... I drill a 1/8" hole at the top of the housing so that air can continuously burp out of the system ..."

... and No Problem with Any Amount of Coolant Leaking ??

.. .. Interesting

No heat question

Reply #24 –
Quote from: AlabamaWildman;458316
Did that, this afternoon, and no new results
Did you see the cable attached to the temperature control lever?

No heat question

Reply #25 –
Quote from: softtouch;458336
Did you see the cable attached to the temperature control lever?

Yes !
... moved the "Adjustment Slider" to the location shown on the Drawings.
The Door can be heard as it closes but Very Little Change in the Air Flow

No heat question

Reply #26 –
Quote from: AlabamaWildman;458338
Yes !
... moved the "Adjustment Slider" to the location shown on the Drawings.
The Door can be heard as it closes but Very Little Change in the Air Flow
The location in the drawing is "pre-set adjustment".
The final "self-adjusting" is the "rapid movement of the temperature control lever to the extreme right of the slot (warm) in the control assembly"
This should slid the clip to where it needs to be to allow the door to move to the full warm position.

Note that the air goes through the A/C evaporator core before it gets to the heater core. If for some reason the A/C compressor is running that will cancel out the heat.

No heat question

Reply #27 –
note on drilling a tiny hole in your Tstat as a failsafe and helping get rid of air..........

make the hole a  tad smaller than 1/8''

in very very very cool temps, you may not make enough heat at the heater core like was my case last winter.

in order to make heat i had to cover 50% of the front of the rad with cardboard to help a little bit.

sorry for the hijack.

in the engine bay there is a tinty iddy biddy black vac line that comes from the vac tree and travels across the fire wall and pops into the cabin on the passanger side.
this is the main vac line source for vac controlled pieces parts in the dash.

make sure that tiny black vac line is connected & not broke or the tree iteself is not cracked.
without this vac source, the interior hvac controlls will not work right,, included in the inspection would be the check valve softtouch illustrates on the EVTM.. this check valve is in the engine bay just prior to where the vac line penetrates the firewall.

No heat question

Reply #28 –
GREAT Info ... Thanks ! !!

Hoping to be able to get that  Dash Loose
(and not having it Shatter due to the Cold Temps !)

No heat question

Reply #29 –
Question:

Does anyone know about the possibility of "Looking Thru" the side of that HVAC Duct ?
... using an Inspection Camera (ala Harbor Freight) and Drilling a Hole only Large enough to allow the camera access ??
without the need of removing the Dashboard ??