gta_knight

Hey guys,

ive done a bit of searching on here but im after more info.

Heres whats happening, when i put the heaters on even after letting the car warm right up, it just blows cool air regardless through the demister vents ! ive checked the hot/cold slider, thats working.

I replaced my heater core about 3 years ago so i know thats ok, ive felt both hoses going to and from the core with the engine warmed up and running and they are hot, so how the hell does cool air come out when the blower has to physically blow through the hot heater core ?

Ive heard people mention a heater valve, im not sure where that is or what it does exactly so any info on that would be helpful thanks.

Im using the car as a daily driver at the minute and its really cold, rainy etc here in England at the moment, the car is just about useless in weather like this because it steams up real quick and i cant demist it.

ImBrandon

Thermostat.

gta_knight

Thats working, i only replaced it last year, and the car warms up normally etc

eseibel67

If both hoses coming and going from the heater core are hot, it's not a cooling system issue, so changing the thermostat won't help. Put the heater on full blast and check outside the car at the base of the windshield on the passenger side. If there's warm air coming up, your blend door is stuck on cold. Reason might be that the hinge is siezed, or the control (either cable or actuator motor depending on model) is not moving it to hot. Blend door is located just above passenger's feet.

gta_knight

I had all of that out of the car last year because my heaters were shot to hell, the air wouldnt come out of the vents etc, so i replaced it all from a scrapped car.

I will have to check the blend door again then, which is gonna be a pain as its a hell of a job getting all the heater stuff in there under the dash apart and back together.

It was working when i put it all back together as i had to unclip the cable from my old one and attach the new one to my controls

chops1sc

The heater control valve might not be working. I had to replace mine not long after I got the car.

gta_knight

Ah right, ive just found out where the heater valve is, i remember seeing it when i was putting all the ducting and the box back in, i didnt actually know what it was though, i thought it was just for the vac lines or something.

does coolant actually go through that thing or is it something to do with the vac system ? i get a bit of hissing from under the dash when selecting different settings but then it fades away.

chops1sc

This part is under the hood.

https://www.thirdgen.org/forums/post...386-post5.html

This is where MOST heater control valves will be located. The actual look might be different from yours though.

Ozz1967

iTrader: (4)

Ditto on the valve, if it's not working, it won't let water flow through the heater core.

gta_knight

oh right ! well in that case i havnt even got one of them, all the emissions and AC was removed on my car so ive just got two hoses too and from the core so theres nothing controlling coolant going or coming from the core ?

today i was sitting in traffic and just out of boredom i slid the hot/cold level back and forth quite hard and i could hear the blend door moving, so i turned the heaters on and i got hot air !!!...........for about 15 seconds, then it started going cool again, WTF..

heres what my hose setup is at the moment, i had to find different ones to keep it away from the headers

Ozz1967

iTrader: (4)

Ok, what you want to do, is take one hose from your heater core, and run it to your intake manifold, there should be a plug on the front passenger side. Then run the other line to your water pump, should be a plug there.

That's how my 84 is set up, it's older than yours and never had the control valve installed (86+ I believe). That will get you hot water, thus hot air.

gta_knight

cool thanks man, ive got a whole day to work on the car this friday so i will have a look then. ive done the throttle body bypass on my car too, i dont know if that makes any difference ?

i still dont quite understand whats going on though, if both hoses have heat in them that means hot coolant is passing through

Richboll

I'd be thinking about insulating or at least moving those hoses farther away from the headers.
Eventually if they don't melt through they will become brittle and break from the heat.

gta_knight

thats quite an old pic, i since drilled two holes in the engine bay and ive cable tied them right away from the headers.

Richboll

Sorry, You said that's what the hose setup was at the moment.

It looks like you have a loop attached to a loop and the water will follow the path of least resistance. You need to hook it up like Ozz says

eseibel67

You also have an engine oil cooler, in which case the heater return line will first run to the cooler then run into the rad, not back to the water pump. Will still work ok, as long as the feed line for the heater is coming from the intake.

The problem you have right now is that the majority of the water is bypassing the heater through the bottom of your "Y" connection. If you want to test it before you take it apart, pinch off that rubber hose on the bottom of the "Y", you should get heat.

gta_knight

ah right, so would i be bypassing the oil cooler altogether with the new hose setup then, if i get rid of the T piece connector and just take the hose to the waterpump ?

So basically the feed and return lines are fighting each other and theres hardly any hot water going through the core ?

Ozz1967

iTrader: (4)

that kind of sums it up. I brought my camera to work today, so I'll take pictures of my set up. You can still run your return line through your oil cooler, just make sure it goes from heater core to the oil cooler and then rad/water pump with the other line coming from the intake and going strait to the heater core.

gta_knight

Thanks Ozz, that would be great if you could do me some pictures mate.

Scott

gta_knight

heres what im thinking first of all, if i remove the little hose thats circled in red, and make the other hoses join together as shown by the purple arrows.

Ive done the throttle body bypass now too so that upper heater hose comes from the bottom of the throttle body, is that ok as the feed ? then it goes through the core and out down through the oil cooler pipes ?

Ozz1967

iTrader: (4)

Here are my pictures. Both hoses go strait to the heater core. Let me know if you have any questions. And yes, if you remove that intermediate hose that you have circled, that should fix your problem.

Also, my older 84, the heater core goes to the water pump. On newer models, Ive heard it runs strait to the radiator instead, which is fine, as long as you have the feed line out of the intake.

gta_knight

awesome thanks a lot mate, i might have to run to the car parts shop and get some new connector pieces and clamps in the morning and try and sort it out, so i'll let you know how it goes, fingers crossed !

Scott

Ozz1967

iTrader: (4)

Glad to help, let me know if you want me to take a "larger profile" picture, further back with a wider view of the engine bay.

gta_knight

Thanks, well i made NO progress today, i went down the the auto parts place i use, i hadnt been for a while, only to find it had closed down ! so i went to another place but they didnt have the right size hose connectors, so i couldnt do anything today, argh.

I checked a few other things though that people had said, i could feel some air escaping from the heater box area and it was cool there too.

I also let the car idle in the garage for a while so it got quite hot, nearly 220 on the temp gauge which is really hot for my car, then i turned the heaters on and got really hot air, but after about 40 seconds it started going cool again....


I guess i wont really know until i sort these hoses out for sure.

One other question guys, that oil cooler above the oil filter where the return line goes too, do our cars really need that ??? mine leaks a little bit and i cant find a replacement, can these just be deleted or will i cause problems by getting rid of it ?

Ozz1967

iTrader: (4)

different topic, but have you heard about the "pontiac owners club uk"?

Pontiac Owners Club UK

eseibel67

Like I said earlier, just clamp off the rubber section bottom of the "Y" as a test. Unless your heater core is plugged, you shouls get heat.

Yes, you can delete that oil cooler. After you remove the oil filter, just unscrew the fitting that the oil filter was holding on to. After the cooler is removed, another fitting for your oil filter to screw onto will be revealed.

gta_knight

I have yeah, im a member on there too, i like a bit of variety though and this forum is awesome.

Thats great if i can just get rid of the oil cooler then, it means i can run the hose straight to the rad instead and get rid of those big metal pipes too.

i'll see if i have something to clamp off the bottom of the little hose then

Ozz1967

iTrader: (4)

A vice grip will work just to check it.

gta_knight

SORTED ! thanks so much guys, as luck would have it a plumber was installing a new shower at my aunties house where i keep the car and he had a load of spare copper pipe which was the exact size for my hoses, so he let me have some to rejoin them

It goes a bit cool if the engine is just idiling but when i rev it a bit, or if im driving it goes hot again, so im pretty happy with that, nice hot air coming out of the demister vents now I'll delete the oil cooler at some point but for now its working so i will just keep it the way it is so i can use the car