[2001 SL2] Losing coolant, but only when A/C is running?

[bigtoque]

I have a 2001 SL2 that I've been having coolant issues with.

First I had the water pump replaced, then still had issues so the shop found out that the radiator fan wasn't coming on, so the fan was replaced. Then there was still leaking, and the shop found the leak on the intake manifold and fixed it. New coolant cap has been installed as well.

I drove the car for a few days and was still losing coolant. Refilled it again, and on a hunch drove without the A/C and surprisingly now there is no coolant loss. Why would I lose coolant when the A/C is running?

One thing that I've noticed is that although the A/C is blowing cold, the A/C clutch is never disengaging and instead it's always on instead of cycling. I don't know what that means. It spins freely when I move it manually, so it's not stuck.

The only other thing I've seen suggested is

• replacing ECTS
• Checking relays
• "Bar's Leaks Radiator Stop Leak Tablets"

When I first had the car in, my temperature gauge went up appropriately as my coolant levels dropped, and now hover between 1/4 and 1/2 with the mostly full reservoir, so it's not likely the ECTS right? If it was working a week ago, it's probably still working today I imagine?

Any thoughts?

[trottida]

I can't think of any direct relationship between the AC and the coolant level. The coolant does nothing from an AC perspective.

If I recall the AC system in the S Series has a variable compressor so the clutch would be engaged at all times. The engagement of the clutch would create an additional load on the engine (and therefore the coolant); so maybe that is the connection. Increased load is forcing the coolant out somewhere.

You need to find out where the coolant is going to resolve the issue. Is there a visible leak or is it leaking into the combustion cylinder and being burned up. Adding UV dye to the system will help find visible leaks using black light and using the appropriate coolant and exhaust tests will find the latter.

The S Series coolant operating temperature is 193 F which in a GEN3 like yours would show on the temp gauge as about 1/3rd. The thermostat cracks open at 188 F and is fully open at 195F. If there is low airflow through the radiator (stop and go; idling) then the fan will kick on at 221F and off at 212 F. For a GEN3 it'll appear just above 1/2 and then drop to just below 1/2.

In my experience, while continuously moving the temp gauge will stay at the 193 F reading. The opening and closing of the thermostat between 188 and 195 will keep it there. Temperature only creeps up if you stop moving or are going slow.

[fdryer]

bigtoque, when running ac, open the hood and check to see and hear the cooling fan running. It must run because the condenser coil gets hot in front of the radiator that's hot too. If the cooling fan doesn't run then the engine will overheat. The fan has its own fuse and a relay.

As mentioned, Saturns run their ac compressors continuously with a variable displacement compressor to lessen engine loads.

[bigtoque]

Just checked and the cooling fan certainly seems to be working. Does the cooling fan have a higher speed that it runs while driving and things get hotter? Maybe there's a relay that's not switching the fan speed (or the fan shuts off while driving)?

I can track down some UV dye and see if I can see where coolant is leaking from. I don't see anything obvious at the moment.

[fdryer]

S-series cooling fans run at one speed. You should hear it loudly. Worn out fans will appear to be working but are slower, reducing the forced airflow thru condenser coil and radiator. There's only one fan relay powering your single speed fan. One member discovered his replacement fan was wired in reverse.

[Waiex191]

Originally Posted by bigtoque

I can track down some UV dye and see if I can see where coolant is leaking from. I don't see anything obvious at the moment.

Check the plastic end tanks of the radiator.