Well, first of all, i have only mild heat coming from my car. I changed the heater control valve, the heater core, thermostat to 195* and i have no air bubbles or leaks, I also checked the blend door and thats not jammed and its not the blower unit. nor do i have any blown fuses underneath the dash, my water pump is working fine also. I took out my center counsil and looked at the heater control unit and noticed a brown wire coming out of the back and it goes into a grey little box, (looks like a fuse but its not) then comes out and i don't know where it goes, but the grey box is chared, like it fried once, i pryed it apart and the wires are still connected but the whole thing is melted inside and crubleing up in my hands, could this be the cause of my heat not working? (i wish i had a digital cam to show you guys) could i just cut out that grey box and soder the two wires together, i don't know why the box is even there. Could this of blown a fuse somewhere else that i didn't check? I have to unplug the vaccume line going to the heater control valve and plug the vaccume line with a bolt in order to get any heat and the heat i get is only mildly warm. Im tired of COLD rides , i don't drive it in the winter but the summer still offers some cold nights. I am about all out of options. maybe my vaccume lines arn't hooked up right at the back of the TPI, i don't know though, does somebody have a diagram of the vaccume lines for the 91 Z28 tpi? I don't have the original hood so i can't look there. SOMEBODY PLEASE GIVE ME AN EXPLANATION, thanks a lot,
KYLE

 

Yup the 3rd gen is good at burning those wires. The problem is the resistance to current has to overcome in the bad connections won't let enough voltage get through the vents.


I just replaced that box / connector with some crimp on male female insulated spade connectors. Worked great for me.


Also, pull both connectora off the back of the heater / AC control head, and check those connectors. Both of mine were burnt up some. I replaced the one connector in the middle with a good junkyard part, and I used female spade terminals on the other ( blower speed switch )




HTH

 

Hey, thanks, i appreciate it. That should be my heat problem though? anyways, thanks again
Kyle

 

Frosty in Delevan,

There are three systems at work to deliver heat:

1. The cooling system must have hot coolant pumping through the heater core;

2. The HVAC temperature and vacuum controls must have the coolant valve open and the mixting/bypass dors set properly;

3. The blower must be running to move air through the heater core.


I understand that the thermostat is a 195°F unit,but do the heater hoses to the core get hot to the touch?

It is also apparent that the air dampers are not binding, but are they moving to the full HEAT position when the controls are set to HEAT?

From reading your post a few times, I couldn't determine if the blower is running on ALL speeds or not. Knowing that would help to eliminate or concentrate on that part of the system.

Another thing to consider is that even though the blower is running, is there any air movement through the outlets? Heater cores can easily get plugged with debris on the air side. Things like all those chestnut leaves from the trees along the lake, grass clippings, mosquitoes and butterflies, etc., can all plug up the air side over the years. (Thats not to mention all the plastic bags and candy wrappers from the damn tourists.)

So, if you can identify which part of the system is the apparent problem, we can probably get it solved fairly quickly.

 

Yes the heater hoses get hot to the touch and yes the door is opeining fully and the heater core is not plugged, i just put in a brand new one yesterday as a matter of fact thats how i know the doors are funtioning properly, i tested them after everything was put back together also. Umm..the blower does work on all speeds and air does blow out the vents or any position (def, floor, ect...) I actually believe it might be the burned up wire, could it not? I don't have any vaccume leaks from inside the dash. I bought the car from my cousin 3 years ago and when i first got it, the heat worked great, then it was summer and i didn't have the heat on but come winter, the heat stopped working, the only way i get heat is if i plug that vaccume line to the heater control valve and it is only kinda warm. I have not done anything different, all of the sudden the heat stops. Can i just cutout the little box and connect the wires together using male and female clips like the guy above stated? That is the only thing i haven't tried yet. I have done the process of elimination and that is the last thing i can think of. I appreciate you guys trying to help me, thanks a lot. Where would i post a cruise control question? i have another story about my cruise control. thanks
Kyle

 

I'm not sure what the little gray box contains or is supposed to do. You can operate the hot water valve manually and hold it open with a wire tie temporarily if you feel that it isn't opening properly by vacuum. That would at least provide full hot coolant flow to the heater core and probably get you closer to eliminating a couple of possibilities.

 

Is it possible that you had hooked some wires up backwards and your fan motor is running in the wrong direction? Just a thought, sometimes when you hook a fans wires up backward it would cause the fan to rotate in the opposite direction.

 

Sounds like this problem has everybody else stumped as well. I checked the vaccume going to the HCV and it does open it properly. My blower works just fine also, its not hooked up backwards, so i am going to cut and wire that bad burned up one and see what happens then. other then that, i have know idea. Thanks for all the help,
Kyle

 

How about a clogged heater core?

 

Just reread your prevoius about the heater core

 

The "little box" is just a connector of incredibly stupid design, nothing more. If your blower works, then it's at least OK enough to supply enough power for that.

Sounds to me like the heater control valve itself is bad.