PAUL T Posted December 22, 2005 Report Share Posted December 22, 2005 In my 94 Concours my heater has not been heating as good as it should. I have checked the antifreeze and it is full and it is a 50/50 mix. I changed out the water pump and thermostat over a year ago. There are no ACP codes showing. What I have noticed is that on real cold mornings (5-20 degrees) the heater will warm slowly always blowing out of the defrost then to the floor. It never blows out of the vents. While the car is driving the air gets cooler. I have to set the climate control panel to 90 in order to get just a hint of warm air with the fan on low. Other times when it is warmer it operates better, almost normal. I can manually make the air come out of the vents with the ACP overrides and I can move the air door. The coolant lines going to and from the heater core are warm. At this point I am suspecting a faulty thermostat (from Advance) stuck open or a partially clogged heater core. Anyone else have any ideas? What is the normal coolant temperature range? Link to comment Share on other sites More sharing options...
BodybyFisher Posted December 22, 2005 Report Share Posted December 22, 2005 I would flush the heater core. My normal operating temp is 197 to 205 in the winter weather. A assume that the aftermarket stat is OK, did it have a long tail on it like the OEM stat did? Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
PAUL T Posted December 22, 2005 Author Report Share Posted December 22, 2005 I would flush the heater core. My normal operating temp is 197 to 205 in the winter weather. A assume that the aftermarket stat is OK, did it have a long tail on it like the OEM stat did? If I remember right it did, but my memory is not as good as it used to be. I may see if I can find my old thermostat and test it. My water hose is winterized right now so if the weather gets warmer this weekend I may see if I can flush the heater core. Link to comment Share on other sites More sharing options...
cadillacjeff7777 Posted December 22, 2005 Report Share Posted December 22, 2005 I replaced my thermostat in my old 93 Seville with an aftermarket once and had similar issues. The collant would only warm up to about 160°F during the winter. I was then told to replace it with a factory one and that cleared up the issue. 2008 DTS Link to comment Share on other sites More sharing options...
adallak Posted December 22, 2005 Report Share Posted December 22, 2005 A stuck open stat is easy to diagnose by touching the upper radiator hose. If it is hard all the time and warms up gradually - your stat is stuck open. If the stat is fine, heater core is the suspect. I have described the flushing procedure for 4.9 (posted some pics as well) a couple of days back. The saddest thing in life is wasted talent Link to comment Share on other sites More sharing options...
PAUL T Posted December 22, 2005 Author Report Share Posted December 22, 2005 A stuck open stat is easy to diagnose by touching the upper radiator hose. If it is hard all the time and warms up gradually - your stat is stuck open. If the stat is fine, heater core is the suspect. I have described the flushing procedure for 4.9 (posted some pics as well) a couple of days back. The 94 Concours is a Northstar. I will check the upper hose. Link to comment Share on other sites More sharing options...
BodybyFisher Posted December 22, 2005 Report Share Posted December 22, 2005 Paul does it come out of the vents in AC mode?, The reason I say this is because I will get a split between vent and floor at times. Maybe you are not getting vent output because its not reaching the commanded temp. Feel the IN and OUT hoses to the heater core and see if one is much hotter than the other, that would be an indication that you have a clog. I am not sure if there is a heater valve on these cars but I dont think so. Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
PAUL T Posted December 22, 2005 Author Report Share Posted December 22, 2005 Paul does it come out of the vents in AC mode?, The reason I say this is because I will get a split between vent and floor at times. Maybe you are not getting vent output because its not reaching the commanded temp. Feel the IN and OUT hoses to the heater core and see if one is much hotter than the other, that would be an indication that you have a clog. I am not sure if there is a heater valve on these cars but I dont think so. Your probably right about the reason the air is not coming out of the vents. We usually have the CCP set on 90 degrees lately, therefore the temperature in the car has never got that high. I will try a lower temp. As far as the heater hoses are concerned, both heater hoses are warm but the flow IN hose is slightly warmer. If I can get my wife to leave the car at home long enough for me to check things out, I could probably have it fixed soon. I will let you know. Link to comment Share on other sites More sharing options...
BodybyFisher Posted December 22, 2005 Report Share Posted December 22, 2005 If I put my C/C on 90 it goes into HIGH fan speed. What is your coolant temp? I would also consider canning that aftermarket stat, if it does not have the long tail on it. Yeah! I was able to post a photo of my OEM stat... Mike Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
PAUL T Posted December 22, 2005 Author Report Share Posted December 22, 2005 I do not think my thermostat had the long tail like that one in the picture. I still think I will replace the thermostat and see if that makes a differance. I turned the fan to low while the C/C was set on 90. Link to comment Share on other sites More sharing options...
BodybyFisher Posted December 22, 2005 Report Share Posted December 22, 2005 Here is a nice photo of the heater hoses from 96, your's is probably similar, Mike Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
justgreat Posted December 23, 2005 Report Share Posted December 23, 2005 don't know if this is applicable to your year caddy but on my 90 seville 4.5 the c/c is programmed to NOT allow heated air to come out of the dash vents; only the defrost or under dash. definitely use oem thermostat.....pig in a poke with aftermarket stuff, but also, try shutting the c/c system off until you reach operating temp (180 or so)...this should help somewhat with getting more heat faster to the heater. jackg 90seville 99k Link to comment Share on other sites More sharing options...
BodybyFisher Posted December 23, 2005 Report Share Posted December 23, 2005 My 91 was that way also, heat was out of the floor vents and AC out of the dash vents. I missed the 'bi/level' setting from my prior cars. My 96 will vary between floor and dash vent to maintain temperature. If I drop the temp a bit, the dash vents will come on. On my 96 the blower will not turn on until the coolant temp reaches about 112 degrees. Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
davedog Posted December 23, 2005 Report Share Posted December 23, 2005 don't know if this is applicable to your year caddy but on my 90 seville 4.5 the c/c is programmed to NOT allow heated air to come out of the dash vents; only the defrost or under dash. definitely use oem thermostat.....pig in a poke with aftermarket stuff, but also, try shutting the c/c system off until you reach operating temp (180 or so)...this should help somewhat with getting more heat faster to the heater. jackg 90seville 99k my 92 eldo has always blowed the heat out the defrost vents on the floor vents, never the dash vents - and so did my 87 deville. Crystal Red Tintcoat Exterior | Shale/Brownstone Interior | 32k Link to comment Share on other sites More sharing options...
Ranger Posted December 23, 2005 Report Share Posted December 23, 2005 My 91 was that way also, heat was out of the floor vents and AC out of the dash vents. I missed the 'bi/level' setting from my prior cars. My 96 will vary between floor and dash vent to maintain temperature. If I drop the temp a bit, the dash vents will come on. On my 96 the blower will not turn on until the coolant temp reaches about 112 degrees. Mike, When you get your Seville, you will get the bi-level feature back. Link to comment Share on other sites More sharing options...
BodybyFisher Posted December 23, 2005 Report Share Posted December 23, 2005 I like that feature Ranger, that's good to know. While it will pain me to let go of my Deville, I am looking forward to an STS...I am sure the pain will go away soon.. Paul, if you don't have the manual, there is a chart titled, Insufficient Heating (Chart 3), if you want it, send me you email address, and I will scan it and send it, Mike PS, we have covered most of the items on the chart, but it may help for you to see it Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
PAUL T Posted December 23, 2005 Author Report Share Posted December 23, 2005 I have got a manual Mike and I have went through most of that chart. That's how I came to either a stuck thermostat or clogged core. I can not find my old thermostat to see what it looked like. Weather is warmer today I may go tinker with it a little. The dash vents do work when you lower the c/c temp. I am not getting any work done today so I may as well work on the car while my wife is not driving it. I will let you know what I find. Link to comment Share on other sites More sharing options...
PAUL T Posted December 23, 2005 Author Report Share Posted December 23, 2005 I just got through letting the car warm up. The thermostat is opening up at 190 degrees then the temp went back to 170 to 175. That sounds a little too cool to me. What do you think? Link to comment Share on other sites More sharing options...
adallak Posted December 23, 2005 Report Share Posted December 23, 2005 I just got through letting the car warm up. The thermostat is opening up at 190 degrees then the temp went back to 170 to 175. That sounds a little too cool to me. What do you think? What is the operating temperature of the stat? The saddest thing in life is wasted talent Link to comment Share on other sites More sharing options...
BodybyFisher Posted December 23, 2005 Report Share Posted December 23, 2005 That is normal when the stat FIRST opens UNLESS it stays at 170 to 175.. Does it stay at 170 to 175? If it did, yes, I agree that is too low and I think you probably would get better heat with an OEM stat... that will maintain the normal temp 20 degrees hotter at 195+.. I think you may have found your problem if the car idles at 170 to 175, Mike I see the outside temp by you is 49 degrees, so if you are operating at 170, that IS too cool, it sounds like that stat is opening too soon. Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
PAUL T Posted December 23, 2005 Author Report Share Posted December 23, 2005 The temperature went to 190 then dropped back to 170-175 at idle and stayed. The outside temperature was 52. I think I will get an OEM thermostat tomorrow and put it in if I get time. Link to comment Share on other sites More sharing options...
BodybyFisher Posted December 23, 2005 Report Share Posted December 23, 2005 That's your problem, I am sure the aftermarket stat is not calibrated correctly for the NS....as someone else mentioned above they had problems with an aftermarket stat.. The guru also stated that the OEM stat is long like it is for a reason... Let me know how it turns out, Mike By the way, its interesting to note that your stat opened at 190 which is BELOW the NS spec of 195 degrees... My 96 will heat up to 215 or so and then drop back to 195 when the stat opens... I will check my opening and drop temps in the morning. I think your engine will be happier running at 195 also, a nice side benefit! Speak to you later, I must work on the TRAIN BOARD! Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
PAUL T Posted February 10, 2007 Author Report Share Posted February 10, 2007 Update I did some more investigating on the heater problem today. Coolant was fine(level and mixture), heater core had been flushed last October, bottom heater core hose was hot and the top was warm, air mix door was working properly, and sensors seemed to be working fine. So I checked under the hood and saw the duct was cracked between the fan motor and the heater core. At first it did not look bad and I was just going to put some duct tape on it and see if it would do it. Well, when I went to clean the duct off I noticed the whole side of the duct was missing behind the coils. There was only the insulation showing. I could have broke it changing the rear plugs a few years ago. It looks impossible to replace the whole duct so, I am looking at fabricating a patch out of sheet metal and sealing it with duct tape. The plastic is pretty brittle so I do not know how extensive the piece missing is because I can not see under the car. From what I can see about a 5" piece from the top to the bottom is missing. I guess the heater works good at heating the engine compartment but not the interior. Has anyone else had this problem? Link to comment Share on other sites More sharing options...
Ranger Posted February 10, 2007 Report Share Posted February 10, 2007 Several others have had that problem. I remember it being discussed before with several good ideas for repairing it. It seems to be rather common in the older cars. Link to comment Share on other sites More sharing options...
PAUL T Posted February 11, 2007 Author Report Share Posted February 11, 2007 Several others have had that problem. I remember it being discussed before with several good ideas for repairing it. It seems to be rather common in the older cars. The plastic is so brittle I am afraid to touch it. I found this thread: http://caddyinfo.ipbhost.com/index.php?sho...mp;hl=hvac+duct I will probably use some aluminum tape and flashing. Link to comment Share on other sites More sharing options...
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