1993 960 wagon with very low heat output

hmcasey · Post by **hmcasey** » 19 Jan 2012, 10:13

Hello, I have a 1993 960. Very low heat output at driving speeds with fan high. When I come to a stop the temp of the air drops even lower. The temp gauge reads normal and in the middle of the range. I have put in a new heater core in the summer, yesterday replaced the heater control valve and of course new coolant. I have a new thermostat in hand but I am having trouble with one bolt stripping on me. Would like to know what else it could be. Could there be a sensor in the heater core box area that might be sending a wrong reading? Mike

hmcasey · Post by **hmcasey** » 19 Jan 2012, 10:21

More info: the coolant hose leading to the thermo is hot to the touch, the two for the heater core are warm but not hot like the thermo hose. Could I have a plug somewhere in the system or a low vacum presure that would only open the heater valve just a little bit. mike

Post by **billofdurham** » 19 Jan 2012, 11:49

When you replaced the heater core did you get all of the air out of the heater system? When draining/refilling the cooling system the heater control must be on max heat. This allows the coolant to pass through the heater core. The coolant must be added slowly and it is advisable to massage the two big hoses from time to time whilst filling the system to prevent any air locks.

The 960 is fitted with Electronic Climate Control (ECC) which incorporates a self diagnostic function. The presence of fault codes is indicated by flashing A/C OFF button. Does the button flash?

Bill.

hmcasey · Post by **hmcasey** » 19 Jan 2012, 12:35

Hello again Mr. Bill. No codes, no flash. Was also thinking the same about air in the system. I think, been a few months, I had the heater on full. If I can get the two thermo bolts off without stripping I will change out the thermostat. If there is air in the system how can I fix it. I ran it yesterday with the cap off, on full heat high. Did this for 20 minutes no improvement. And today it was -11 out and I was frozen driving into work. Mike

hmcasey · Post by **hmcasey** » 20 Jan 2012, 06:59

Another thing I have noticed is the ACC isn't working properly. When I have it in ACC mode and on and high temp heat, the fan stays low like it doesn't read the proper temp. Does the coolant temp sensor send a value to the acc and control how much the fan kicks on. My thinking is that if there a problem with a reading from the engine ie, too cool of coolant temp, and the acc is on auto, it wouldn't kick the fan and heat high until the temp gets hotter. Is my thinking right?

Post by **billofdurham** » 21 Jan 2012, 11:55

If the temp gauge is reading normal I would think that the thermostat is OK. If you do have an air lock in the heater the best way forward is to ensure the control is on max heat and drain the system. Then refill slowly massaging the two big hoses from time to time to stop another air lock.

With regard to the fan; does it work at a high speed if you set it to 5?

Bill.

lilmikeyzz · Post by **lilmikeyzz** » 22 Jan 2012, 22:15

just a quick question: have you actually watched the heater control valve operating to make sure it's really working? My wife's 95 960 has slowly produced less heat over the last couple years. Today I finally took a look and determined that the control valve was not moving. Did I get all wonky and try to figure out why? Heck no (it's my wife's car after all), I just zip-tied that sucker open and voila, full heat. I imagine that if your valve isn"t moving it's probably due to low vacuum. My wife's has a vacuum leak somewhere in the depths of Underdash but i've been loathe to go there.

hmcasey · Post by **hmcasey** » 30 Jan 2012, 10:16

Problem fixed!!!! I had the "hot"/"cold" lines switched for the heater core. Now I have sweet heat. Thanks everyone for the help. Mike

Post by **billofdurham** » 30 Jan 2012, 12:03

Thank you for the update.

Bill.