2004 LeSabre intermittent heat?

[ewb4arch]

I've googled around for the usual issues but still haven't figured it out.

Looking for ideas. This 2004 LeSabre is new to me. The heat is intermittent. Generally speaking, it is slow to blow warm, sometimes hot air. The temp gauge seams to warm up as you'd expect. I checked the blend damper and it seems to move how it's supposed to (checked when cold).

It was a little low on coolant, but does not seem to be loosing any after I added some. There is evidence of collision damage, I think it may have lost coolant from an accident and was never fully topped off after the repairs.

I'm at a loss as to what else to check. The fan blower motor seems to work fine. Switching to recirculating seems to make it worse, colder seeming air coming out. Could a partially clogged heater core cause intermittent heat?

The climate control unit seems to be a used replacement. Is there some sort of calibration procedure required when that is replaced? I don't see how that would cause intermittent heat though.

The last think I could think of is the blend damper being flakey and only working right sometimes?

 

[BuickGirlFromMars]

 

[ewb4arch]

Thank you so much BuickGirlFromMars! Seems like the calibration procedure is what I'll need done. The 2nd one is talking about automatic climate control. My car doesn't have that, it has the old school slider like this the attached.

Like I said, I think this unit was replaced. Is my 2004 "custom" trim level, cloth seats supposed to have the automatic climate control? Any way to know for sure? Would getting a automatic control unit possibly solve this issue without the calibration procedure? Those are going for about $35 used vs at least 30 minutes labor at a shop.

 

[BuickGirlFromMars]

Thank you so much BuickGirlFromMars! Seems like the calibration procedure is what I'll need done. The 2nd one is talking about automatic climate control. My car doesn't have that, it has the old school slider like this the attached.

Like I said, I think this unit was replaced. Is my 2004 "custom" trim level, cloth seats supposed to have the automatic climate control? Any way to know for sure? Would getting a automatic control unit possibly solve this issue without the calibration procedure? Those are going for about $35 used vs at least 30 minutes labor at a shop.

custom likely came with manual controls so you need not worry about that aspect. your car isnt set up for an automatic system it wont work