Heater not getting hot enough
 

On my 2000 Monte carlo SS 3.8 3800 series I noticed my heater gets warm, but doesn't get so hot where I have to adjust the temperature from the heater controls. On my moms 2004 Monte Carlo, her heater gets hot after a few minutes. Mine it took like 10 minutes. Sometimes it gets really hot, then it gets warm. A guy at work thinks it's the thermostat, but my engine temp guage is fine. Sometimes it does take longer for the engine temp gauge to get higher. My dad thinks it may ne something under the hood because they used to have a 1975 Monte Carlo which had a similar problem with heater not blowing hot enough air. He said it wasn't the thermostat, but something else under the hood. Does anyone know what could be the problem?

check the t-stat. might be sticking

When was the last time the coolant was flushed?

The coolant does look sluggish, I'll flush it

If you are doing it yourself, flush it completely and run water in it for a little bit. Then drain the water and run water again. Repeat a couple of times until the water is coming out clean.

Then fill it back up, and you might as well replace the thermostat too. It's a piece of cake, and cheap.

Then just bleed the system completely and you should be good to go.

i say t-stat

The last thermostat was an aftermarket, so I got one from the dealer for $12.50. After that, my heat got really hot. I don't need to flush my coolant. The sluggy stuff was in the plastic reservoir not in my system so I should be ok. I also had a problem with a loud noise coming from my belts. I figured it was an idler pully since my alternators are new. turned out to be a bad bearing on my ac compressor. To avoid spending $105 having my ac recharged, it loosened up the compressor without disconnecting the lines to change the bearing. I had to make my own shallow gear puller to pull off the clutch. Most of the noise went away. I still have to replace the idler pulley because it still makes a little noise under the hood.

If you don't know the last time the coolant was flushed you should still flush it.

I agree with Chibi! All coolant (green and Dex) need flushed periodically. Otherwise, it contains contaminants like rust and scale. Plus it's lubrication properties and anti-corrosion agents brake down. This results in clogged radiators and heater cores AND the fluid itself becoming sludge in different parts of the system.

You noted it looks like sludge in the overflow bottle. If it's sludge there you probably have sludge in other parts of the system. Time to get it out.

It's all part of good maintenance.

I replaced the thermostat and my heater gets hotter now. I used a thermostat from the dealer for $12.50