[TheJoe]

Weird thing started happeneing

my heat will turn off and only cool air comes out, usually happens after about 10 mins or so of driving and wont come back on until after i turn off the car for 5 mins or so

i did notice it would sometimes loose heat when i would make a hard left turn.

i looked at the heater control valve and it looks fine, i just pulled the vacum line to see if that is it and will see what happens on the drive home today.

Partial Post: Please Login or Register to read the full post.

[TheJoe]

well i disconnected the vacum line and the heat still went cold on the way home, right after i touched the control unit. so i swapped out the control unit last night. i went to reconnect the vacum line and that broke so i will be replacing the whole hard flexible line back to the firewall. so far on the way to work today the heat stayed on.

Partial Post: Please Login or Register to read the full post.

[flash]

weird. the HCV works opposite of that. when there is a vacuum leak, it defaults to the "ON" position.



more likely it's at the control mechanism inside the car. that is known to have a clip fail that causes all sorts of weird operation.

Partial Post: Please Login or Register to read the full post.

[TheJoe]

flash is that the control unit i just changed or is that something under the dash?

Partial Post: Please Login or Register to read the full post.

[flash]

the heater control valve is under the hood. not sure if that's what you changed or not, but it defaults to "ON", so you would have heat all the time if the vacuum line broke there.



the main control unit is under the dash. that's where your problem may be.

Partial Post: Please Login or Register to read the full post.

[Grandpa#3]

Hi Joe, The link below for Clark's Garage Heater Trouble Shooting should cover your problem



http://www.clarks-garage.com/shop-manual/hvac-01.htm





Cheers,

Larry

Partial Post: Please Login or Register to read the full post.

[TheJoe]

thanks Grandpa, i did look at that and did think it was air in the system but the way it would go from hot to cold so quickly i didnt think it was that since it would do it on the highway and at idle. I replaced the control unit on the dash (fan and temp control) last night and with driving it thismorning the heat didnt go out but i will drive it more to make sure. i bought some hard vacum line to replace the brittle line i broke this morning

Partial Post: Please Login or Register to read the full post.