94 sc400 heat question
Lexus Champion
Joined: May 2002
Posts: 2,781
Likes: 6
From: Georgia
I'm having similar issues.
At this point I feel that air in entering my cooling system somewhere, not allowing for a compete vacuum.
My heat is RPM dependent. At 900rpm it blows cold air, at 1500 warmer air, at 3000 the air is HOT.
My valve is working properly. I tested it by turning on the heat and feeling the backside of the valve to ensuring the vacuum is pulling it closed. When cold air is selected it opens as normal.
I'm almost certain the heater core has finally opened up large enough to let enough air in to cause problems.
Otherwise I'd say its a radiator cap.
The overflow was bone dry, I added coolant and it won't get pulled into the radiator, so there must be a air leak somewhere.
At this point I feel that air in entering my cooling system somewhere, not allowing for a compete vacuum.
My heat is RPM dependent. At 900rpm it blows cold air, at 1500 warmer air, at 3000 the air is HOT.
My valve is working properly. I tested it by turning on the heat and feeling the backside of the valve to ensuring the vacuum is pulling it closed. When cold air is selected it opens as normal.
I'm almost certain the heater core has finally opened up large enough to let enough air in to cause problems.
Otherwise I'd say its a radiator cap.
The overflow was bone dry, I added coolant and it won't get pulled into the radiator, so there must be a air leak somewhere.
After inspecting my radiator cap I found that the rubber felt as hard as plastic and was dry and cracked. So I replaced it with another cap I had laying around for now.
I removed the upper radiator hose and manually poured coolant into the engine until it overflowed, then switched the hose around and manually poured coolant into the radiator until it was filled the end of the hose and I stuck the hose back onto the inlet into the engine.
I was over 1 gallon low on coolant. But the system had an airleak and so the coolant in the overflow could never get pulled into the radiator.
If you have an air leak, no amount of fluid poured in the overflow will ever make it into the radiator.
I now have HOT heat all the time.
I removed the upper radiator hose and manually poured coolant into the engine until it overflowed, then switched the hose around and manually poured coolant into the radiator until it was filled the end of the hose and I stuck the hose back onto the inlet into the engine.
I was over 1 gallon low on coolant. But the system had an airleak and so the coolant in the overflow could never get pulled into the radiator.
If you have an air leak, no amount of fluid poured in the overflow will ever make it into the radiator.
I now have HOT heat all the time.
Thread
Thread Starter
Forum
Replies
Last Post
treeman
LS - 1st and 2nd Gen (1990-2000)
3
Jan 24, 2010 11:51 AM
