01 Saturn Heat

[NYEngineer]

Ok, here's one that has me talking to myself. My wife's 01 Saturn L300 has the Opel V6. She got a new engine in July. The other day, she got in, turned on the heat for the first time since the new engine and had NO heat. When I got home, I began checking it and found a 12 volt pump on the back of the engine to pump hot coolant into the heater core. I checked it and it was bad. No brainer, I think. I go to the dealer, pump is no longer available, they hand me a pipe elbow, a revised hose, two wire ends and a printout of the pump not necessary bulletin.
So... I install all of this junk to the letter of the bulletin and noticed the engine and heater core was hopelessly airbound. I bled all the air out and still had cold air. Finally, I noticed the AC compressor is on. The Air conditioner button is off, but the compressor is turning. It seems like a control problem. Anyone ever seen anything like this?

 

[JTK]

Never heard of the coolant pump. It does seem odd that it was built that way, but you really don't need it? As long as the heat output is good, one less part is good! The a/c compressor cycling sounds perfectly normal. The compressor will cycle on any of the windshield defrost settings & some auto climate control systems cycle the compressor any time the blower is on. You'll notice the compressor wont run if ambient temps are below 50° or so.

Joel

 

[NYEngineer]

Thanks for the reply. Yeah, oddly enough, both heater hoses go back to the same housing, so I have no idea how it flows through the heater core and back. Even though I'm getting hot water to the core, the defroster still only blows cold air as does the heat. I'm guess ing now that maybe some diverter isn't changing position or something. Guess I gotta go in the dash.

 

[JTK]

Do you get heat out of the other dash settings? Do all the dash settings push air where they are supposed to when selected? I'd also verify if both the in and out (of the heater core) hoses feel hot. Maybe it's just air lock? or if you've got vacuum actuated blend doors, maybe a vac line got knocked off during the engine swap?

Joel

 

[NYEngineer]

JTK, the coolant is NOW circulating through the core. It was hopelessly airbound but I finally got it. No heat comes from the ducts on any setting. I'll get in there tonight and make sure everything is connected. I've been looking, but it's always in a rush before she's getting ready to go somewhere.