ricrice Posted December 19, 2009 Report Share Posted December 19, 2009 I have a 99 SLS with 70,000 miles on it. My problem is that I get no heat. The fan comes on but no heat. Last year I had a dealer look at it, they replaced the cabin filters but that didn't help. Any idea's Thanks Link to comment Share on other sites More sharing options...
Texas Jim Posted December 19, 2009 Report Share Posted December 19, 2009 Pull your codes and post them here. Look at the "HOW TO" at the top of the page. Link to comment Share on other sites More sharing options...
PAUL T Posted December 20, 2009 Report Share Posted December 20, 2009 Could be clogged heater core. You can check this by taking off the hoses to the heater core and back flushing with a water hose. Check to see if your plastic heater box cover is still intact. On some models the plastic gets brittle and breaks up. Look around the fan motor to see if there are any broken pieces. Also if your antifreeze is not at 50/50 this will cause heating problems. Link to comment Share on other sites More sharing options...
adallak Posted December 20, 2009 Report Share Posted December 20, 2009 Also if your antifreeze is not at 50/50 this will cause heating problems. Why? The saddest thing in life is wasted talent Link to comment Share on other sites More sharing options...
JimD Posted December 20, 2009 Report Share Posted December 20, 2009 I have a 99 SLS with 70,000 miles on it. My problem is that I get no heat. Could be any number of conditions from a clogged cooling system air purge line to mix door actuators inside the cabin. You can narrow down the shopping list of possibilities by displaying your Diagnostic Trouble Codes (DTC); here's how-to for your 1999 Seville. You are most interested in "B" codes. Write them down and post them here. http://www.caddyinfo.com/readingcodes.html Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
airmike Posted December 20, 2009 Report Share Posted December 20, 2009 a simple but overlooked cause could be low coolant. Your car can be low enough to prevent the heater from getting hot without the gauge showing overheated. A sure sign of low coolant would be if you rev your engine and you can get warm air. Link to comment Share on other sites More sharing options...
Ranger Posted December 20, 2009 Report Share Posted December 20, 2009 Straight water will provide just as much heat as a 50/50 mix will. Low coolant should trip the CHECK COOLANT LEVEL message long before any air gets into the heater core. Link to comment Share on other sites More sharing options...
PAUL T Posted January 2, 2010 Report Share Posted January 2, 2010 Also if your antifreeze is not at 50/50 this will cause heating problems. Why? It has to do with the outside temperature. If a car has more or less than 50/50 it causes the antifreeze to freeze quicker in cold weather conditions say around 0 to 20 degrees. All I know is when I had this problem in really cold temperatures the Guru pointed this out to me. Link to comment Share on other sites More sharing options...
adallak Posted January 2, 2010 Report Share Posted January 2, 2010 Also if your antifreeze is not at 50/50 this will cause heating problems. Why? It has to do with the outside temperature. If a car has more or less than 50/50 it causes the antifreeze to freeze quicker in cold weather conditions say around 0 to 20 degrees. compared to what? The saddest thing in life is wasted talent Link to comment Share on other sites More sharing options...
joeb Posted January 2, 2010 Report Share Posted January 2, 2010 make sure coolant level is ok. than get motor to operating temp. check heater hoses thru firewall to see how warm they feel. if they are hot, than heater core is probably ok. the next step would be to check air blend door under dash. Link to comment Share on other sites More sharing options...
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