No Heat Getting Chilly Outside

Discussion in 'The Big Chill' started by Rich Skylark, Sep 14, 2020 at 11:30 PM.

  1. Rich Skylark

    Rich Skylark Gold Level Contributor

    My 68 Skylark has no heat at all . Recently went through HVAC system after dashboard resto and addressed the following. Removed , cleaned control unit ( original A/C car ) , all vacuum lines inspected and changed where needed , blower switch-wiring- resistor plug changed . All 4 blower speeds work and likewise all the ductwork/hoses was gone through and replaced as needed . Heater core was back flushed ( very dirty now clean ) . New heat/ defrost cables from Old Air were installed with limited success. Heat cable was straightforward but blue defrost cable is too long making it impossible to connect to defrost door . The defrost and heater doors do move freely when manually opened. The vacuum switch on the fan speed switch was also changed. Car was purchased a few hrs ago but the wiring/ vacuum lines were a mess . Because of this the HVAC system never worked . Heater control valve was leaking and changed when purchased. Currently with heat door wide open in heat position I have no heat . The incoming heater hose is decently “ warm “ the return is cold . Radiator is full with new 160 thermostat. Thought I went though everything but I’m missing something. As always any and all opinions welcomed.
     
  2. jaye

    jaye Well-Known Member

    Sounds like your control valve is not opening. It operates off vacuum solenoid. That’s the way my 69 operates
     
  3. Rich Skylark

    Rich Skylark Gold Level Contributor

    I applied 30 lbs of vacuum to the HCV It did get warmer but did not result in heat . This nasty stuff came out of my heater core C027E0C6-AFC8-40A1-9541-46878FE8D8EF.jpeg
     
  4. Brett Slater

    Brett Slater Super Moderator Staff Member

    I think it's safe to say that 52 year old heater core is on the list for your winter projects.
     
  5. Mart

    Mart Gold level member

    Run a straight hose from heater core to intake, eliminating control valve. See if you get heat.
     
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  6. Rich Skylark

    Rich Skylark Gold Level Contributor

    I’m at work with the car and that’s my lunch time project . Off hand do know the size of the fitting that goes into manifold where the HCV is located ?
     
  7. Rich Skylark

    Rich Skylark Gold Level Contributor

    Was curious Brett, all of that crap came out initially when I turned on the hose . In 5 minutes it was crystal clear with no leaks . Do you think it is necessary to replace the heater core ? Can there still be blockages in it ?
     
  8. Brett Slater

    Brett Slater Super Moderator Staff Member

    It's possible, yes.

    You could always bypass it to finish out the season. Just bundle up like I did with mine for a couple years before putting in the new core two summers ago.

    Every one of these cars will absolutely need to have this part replaced at some point. It's inevitable.

    You can be proactive and make it a winter project or wait until it pisses all over your passenger's side carpet. That's usually how it happens.
     
  9. Mart

    Mart Gold level member

    Was it leaking on your pass side carpet, or steaming up your windows on the inside? That's the time for replacement imo.
     
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  10. Rich Skylark

    Rich Skylark Gold Level Contributor

    Owned car 6 yrs purchased from original owner_- southern car , like I said the fan switch wiring was a disaster and most of the 7-8 vacuum lines were cracked from age . Both control cables were broken. Amazingly when I got it home ; when I removed the a/c lines while detailing the engine , a full charge of R 12 escaped into the air. I immediately closed it back up and noticed the compressor moved freely - all good signs. That’s for another day .Just got it back on the road after 3 yr mini restoration and otherwise looks very good ( not perfect) and is a pleasure drive . HVAC system has never worked since I owned the car and with first cold weather here now the heat is first up . Changing the core if it has to be done is will be , but seemed to be cleaned out when flushed with no ill effects .
     
  11. 12lives

    12lives Engage! - Jean-Luc Picard

    Make sure you have the correct control valve. Some open with vacuum, some close with vacuum. They look the same on the outside. As said above, bypass it and see what happens.
     
    Mart likes this.
  12. Mart

    Mart Gold level member

    ⬆️⬆️⬆️Yep, wrong control valve will not open.
     
  13. Rich Skylark

    Rich Skylark Gold Level Contributor

    Going to try bypassing the valve tonight. For what it’s worth is there a tell the difference between the 2 types of valves ?
     
  14. Dr. Roger

    Dr. Roger Stock enthusiast

    Also check your timing. If it is way too advanced, the engine will never get warm enough for the heater to work.
     
  15. Rich Skylark

    Rich Skylark Gold Level Contributor

    Just went through the timing- was running too hot . New vacuum advance and changed distributor springs car is running better than it ever did . Going to bypass the heater control valve tomorrow and eliminate that possibility. Will update tomorrow
     
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  16. 12lives

    12lives Engage! - Jean-Luc Picard

    Blow through the valve with no vacuum and then with vacuum. Of course it has to be off the car...
     
  17. Rich Skylark

    Rich Skylark Gold Level Contributor

    Bill you mean with compressed air Blow it through the vacuum port ?
     
  18. 12lives

    12lives Engage! - Jean-Luc Picard

    No - blow through the water port. That will tell you if it is open. I just use my lungs. Test it with and without vacuum.
     
  19. Rich Skylark

    Rich Skylark Gold Level Contributor

    Found the problem - no vacuum to the HCV . Took the valve off , cleaned it up And noted when I applied vacuum to the port on it the valve was moving . I plumbed into the manifold some 3/8 black pipe with an adapter to my heater hose & like that 85 degree heat . The last issue is to solve is how to hook up the defroster door cable. The heater door ( red ) cable is a PITA - to put it mildly, to connect to the control unit. The defrost door cable ( blue ) as I see it can’t be done. The distance from where the cable attaches to the door is 8” The cable I have from Old Air is 30” . Called the company to verify cable is correct for 68 Skylark w/ A/C and was told it was . Interesting No one in the technical dept had any insights into installing it . 1968 HVAC controls was a one and done bad idea as most 68 owners will attest to . If any one has any thoughts on or has done this cable install would like to hear them .
     
  20. 12lives

    12lives Engage! - Jean-Luc Picard

    One trick to working under the dash is to pull the seat out. Then you can lay down on your back and reach everything.
     

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