96 TA with No Heat Please help

[boater454]

I need to pick your collective brains on this one. First I'll tell you what does work. The fan, The A/C, New thermostat works fine, New radiator cap, new Water pump. Burped system several times to be sure air is out. It just doesn't blow warm heat. With an infared thermometer the heat duct reads about 85-90. should be 150 or more. The hoses into and out of the heater core are both at full temp.

I think it could be a flapper door that's allowing too much outside air in but then I don't under stand why the A/C will work so well on a hot day.

Any suggestions on what to try next?

Thanks

[TEAMGAROOT]

check your vacume hoses? i once forgot to reconnect a vacume hose after i put a new engine in, it controled my heater selector swich and screwed me up for a few months.

[firebirdfrk]

I have a 95 and had the same problem, it turned out to be a small vaccuum check valve that had gotten brittle and broken. The valve worked with the blend door.
The new art only cost a couple of dollars. I was located close to the PCM on the pass. side of the engine compartment.

[boater454]

Thanks, I'll do a vacume check and let you know

[tank123]

if the vacuum lines check out. chek the vacuum switch on the heater control. if it is bad a lot of times you will hear a hissing sound coming from that area with the car running. that vacuum switch controls the blend air door

[housy_bigmike]

check your heater core

[chevycruizer]

i have a 95 with the same problem. I know my door is working. I have the factory books (over $200). it says you can check the heat door by quickly turning the control knob from full cold to full hot. you should hear the door thud. well mine is working. still no heat. i did pull both of my heater hoses off of the heater core and i ran water through the core to see if it was plugged and it was fine. at the same time i replaced the hoses (they were getting soft and the end had a bubble in it) i tried new hoses because there is a heater control valve in one of them. it does not look like any other heater control valve i have seen. it has no vacume hoses or cables or anything. it is just a small plastic piece with a smaller plastic piece it. i also tried a new water pump and thermostat, bled the system numerous times. i have given up and parked it for the winter.

[chevycruizer]

i just went out and checked my check valve that firebirdfrk mentioned. is the one that is mounted near the pcm and the ac hoses. mine is fine. you can easily tell if that is your problem, here is how. turn you blower fan on high with the car running. turn the ac-heater select switch. if the air changes locations it is fine. if it stays on defrost you have a problem. the defrost is the default location. so if the air transfers from floor to vent to defrost you do not have a vacume leak. also the heater door on this can is not vacume controlled. so that theory goes out the window also.

[boater454]

Thanks,
My air does change from defrost to vents to floor. About the Heater Core - If line temp in and out of core is good do I need to check it any further? I'm still concerned it could be the air mix door. What's the best way to check this? I don't here an audible thump. Thanks

[chevycruizer]

the thump on mine is quite noticible. so that may be a good place to look. it has been a while since i have had mine off but i think you have to take the passanger footwell cover off. then you will see a cable and a circular hook up for it. have an assistant turn the heat knob back and forth while you are laying upside down in the passanger footwell area and you should see it. if i have free time i will look at mine today and get a better description.

[CreepingDeath94]

The temperature at the inlet and outlet of the heater may be deceptive. The heat could seep from both ends and appear to be hot like it is flowing but it may be clogged or not flowing properly. If you were checking the heat of the inlet and outlet hoses to the heater core, make sure you do it from cold engine to hot and see if the outlet warms up at the same time as the inlet.

[Rmbodie]

My 2000 TA engine warms up fine but when I crank to have a warm car when I get in , it is only blowing cold air until I start moving the car . Defeets the effort . Rob

[boater454]

Mine's kinda the opposite of that. It's blow luke warm air while standing still but then cold when I move. A dealer told me that they have to put the nose up at a 45 degree angle for 48 hours sometimes to bleed the lines of all air. Anyone ever heard of this?

Thanks