Heater trouble: 1995 Vette C4 Base Coupe

[Argulace]

The heater in my car blows luke warm, not even warm enough to be considered definately warm, no matter how high the temperature is set on the control; including 90 degrees (max).

AC works fine, vent works fine, defrost is same temp as the heater (again regardless of the setting on the dash). The air changes to the floor vents properly when I change the setting to the heater, it also changes to the glass vents when I change to defrost, so I know at least the directional parts are working.

Any advise? Thanks!

 

[Rabbit]

You can check the basic functions by holding the Fan up arrow & the fan down arrow at the same time for approximately 5 seconds. The LDC display should show "-00".

Push auto fan & the display will show any trouble codes.

 

[Argulace]

You can check the basic functions by holding the Fan up arrow & the fan down arrow at the same time for approximately 5 seconds. The LDC display should show "-00".

Push auto fan & the display will show any trouble codes.

I checked for codes as you suggested, I got 00, all clear. I guess it has to be something mechanical then?

I also noticed (because it's getting colder) that my defroster has almost the opposite affect that it should. This morning I started my car, defrost on full blast at 90 degrees, it sat for 10 min idling, I could hear the compressor kicking on, the windows were still frosted after all that time. I felt the air after switching it to the floor heater and leaving the temp set to max, it was cool, only slightly higher temp than the air outside.

Any help or suggestions would be much appreciated.

 

[Rabbit]

I checked for codes as you suggested, I got 00, all clear. I guess it has to be something mechanical then?

I also noticed (because it's getting colder) that my defroster has almost the opposite affect that it should. This morning I started my car, defrost on full blast at 90 degrees, it sat for 10 min idling, I could hear the compressor kicking on, the windows were still frosted after all that time. I felt the air after switching it to the floor heater and leaving the temp set to max, it was cool, only slightly higher temp than the air outside.

Any help or suggestions would be much appreciated.

PM sent regarding diagnosis procedures.

 

[Argulace]

Update

PM sent regarding diagnosis procedures.

Here is an update on my progress.

I took the wiring harness clip and three screws holding down the plugs for the blower motor relay out so that I could see the blend door flap from the inside of the engine compartment. I had my wife sit in the car and turn the heater on and off, watching the door open and close fully. Verified, door works! No problems.

Ok, after having Rabbit give me some advise on blockage I verified the temperature of the inlet and outlet (return) hoses for the heater core. One warm, the other warm but cooler. Hmm, there IS flow but is there enough?

I started squeezing the hoses repeatedly, like what you do when you have just flushed the system and you are trying to work the air out of the radiator, and block; only I was squeezing the return and inlet hoses for the heater core.

I noticed the pressure would sort of release a little when I squeezed, then build back up. After having squeezed the hoses about 30-40 times each I started to realize that the system IS at least partially blocked.

I went to the grocery store and bought a bottle of CLR. Since CLR is a safe chemical and doesn't harm gaskets, rubber, plastic or metal; I poored the whole bottle in to the cooling system, ran the car for 15 minutes and checked the heater again.

There is warmth. Not what I would call "HEAT" but on a scale of 1-10 I am getting at least a 2, where before I was somewhere in the negative. Progress? I am going to run the car for 2-3 days with the CLR in there to see if there is progress, if there is I'll wait until I feel that the system is clear and flush the cooling system all together.

That's the latest.

 

[Argulace]

Update #2

Fixed! 1 bottle of CLR. Done. My heater went from ice cold to hot enough so that I can't keep my hand in front of the floor vent comfortably. It's blowing HOT HOT air now.

As an added bonus, my average running temperature has gone from 205 to 185. The CLR has only been in there for about 3 hours. I'm going to leave it for another day, let it REALLY clean the thing, then I'll flush it.

Thanks for the help Rabbit!

 

[Rabbit]