Heat weak Electronic Climate Control 96 RMS

[PatchogueMan]

I own a 1996 Roadmaster Sedan with electronic climate control, I also have a 94 Roadmaster Sedan also with electronic climate control. I remember having this problem in the 94 sedan, and I am having it now in the 96. The heat is not effective when the fan is set to highest setting, nor when the defogger is turned on. I have checked the coolant level in the overflow tank, and the level seems OK. I know that the control module in the 94 Sedan had to be replaced, I think it was also replaced on the 96 Sedan. When I drove the car today (freezing cold on Long Island today), and if I kept the fan setting as low as possible, and only used the floor vents, we had heat. If I changed the flow to either middle or defog, and turn the fan to a higher setting, the heat fades quickly. The air is not ice cold, but really doesn't "do" anything for a cold interior. In the 94 Sedan I had the heater core blown out several times, that really didn't help all that much. I have not done that on the 96 Sedan so far. Does anyone else have this problem? The A/C worked fine this summer, and there was a noticeable change if I raised the temp on the A/C (definitely got warmer) during the summer. Does anyone know if the Climate Control Diagnostics has something to do with what the heater considers "hot"?

 

[200OZ]

IMO you need to replace the heater core, remove the knock sensers in the engine block, and flush the system VERY well. These LT1 B body's are notorious for bad heat from accumulated crap in the cooling system clogging the core. Flushing usually helps, but only temporarily, like days temporarily. I've flushed a few of my B LT1 cars 5 or 6 times, and the core still plugs up. Your heat works on lower fan speeds because you still have coolant flow through the core, just not enough to maintain heat with higher air flow from the blower motor. Good luck.

Mike

 

[petermholmes]

In the 94 Sedan I had the heater core blown out several times, that really didn't help all that much. I have not done that on the 96 Sedan so far.

If "blowing out" the heater core on your '94 didn't make what came out of the floor vents hotter than h*ll then something wasn't done right. You need to do an old fashioned cooling system flush with nice old fashioned cooling system cleaner and a full rinse before you blow the crud out of the heater core. When you do blow out the heater core, you have to blow into the outlet so that the crud comes out the inlet.

The '96 models came with Dexcool installed which wreaked havoc with my heater cores. In 3 years my '96 (bought new) went through 3 heater cores. The second it went off warranty I had the system cleaned thoroughly (including the heater core) and the Dexcool crap replaced with old fashioned antifreeze. That reduced the problem to "clean the system every two years and you'll always have good heat".

 

[71novaguy]

I hope thats all the issue I am having also. I known when I replaced the radiator, it seems most of the coolant was water and rust. I changed the coolant again when I replaced the water pump about 2 weeks later and there was still a good amount of rusty color to it. When I set the heater on 90, it feels more like 70.

 

[krazykrames]

I had the same problem, flushed heater core good with a garden hose and has been fine for the last 3 months. It's so hot I think it would burn your hand if you held it in front of the vent.

 

[71novaguy]

well it seems to have fixed my issue. When I first started flushing, the resistance to the water flow was so great I was getting spray back around the garden hose (spraying me all over). Flushed it one way, then backflushed. Went back to the original orientation and no more resistance!

I flushed it until it was mostly clear water, then pushed some compressed air through it. Seemed to stir up more crap cause when I hit it with water again, it was dirty then would clear up. Did this for about an hour, hooked the lines up and ran it. Got nice hot heat again.