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2000 Catera Sport
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390 Posts
Discussion Starter #1
Now that fall is about here, we had a cooler day and my heater all of the sudden doesnt heat very much. I put a thermometer in the vent and the highest it got was 85 degrees. My Dodge Neon was at 110 before it was at operating temp. I recently changed the auxiliary water pump. (The one on the radiator, drivers side) All went well with that. The coolant is full in the reserve tank. I didnt purge the air out but I heard you dont have to in these cars. (If theres an easy way to do this let me know.) If I change the temp to 60 degrees and then back to 90, the temp doesnt go higher than 80 degrees. So it seems like I gotta set it to 90 when I first start the car and not touch it or else the heat stops working all together. I also had the A/C compressor replaced a few months ago also. I also did the reset technique via pressing the on/off and auto buttons for 5 seconds with just the ignition on. Where do I start with troubleshooting this? Thanks
 

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1997 Catera
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172 Posts
1) Check the operation of the heater control valve. At 60 degrees it bypasses the heater core entirely, at 65 or higher it allows fluid to flow. If it is plumbed wrong (mine was) it switches the heat OFF above 60. Quick test - get car up to temp, then move temp to 60 for several seconds then back up to 90, see if there is a quick burst of warm air before it gets cooler again.

2) You replaced the aux water pump (on radiator) - did you check the heater aux water pump on the passenger side fender well? No flow here and your heat will be minimal.

3) There could also be an issue with the actuators under the dash that direct the cold and hot air. Several posts are on this forum on how to get to the actuators and fix the loose screw that keeps them from shifting. Fix the screw to re-engage the linkage and then re-sync them as you described in your first post.
 

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2000 Catera Sport
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390 Posts
Discussion Starter #3 (Edited)
1) Check the operation of the heater control valve. At 60 degrees it bypasses the heater core entirely, at 65 or higher it allows fluid to flow. If it is plumbed wrong (mine was) it switches the heat OFF above 60. Quick test - get car up to temp, then move temp to 60 for several seconds then back up to 90, see if there is a quick burst of warm air before it gets cooler again.

2) You replaced the aux water pump (on radiator) - did you check the heater aux water pump on the passenger side fender well? No flow here and your heat will be minimal.

3) There could also be an issue with the actuators under the dash that direct the cold and hot air. Several posts are on this forum on how to get to the actuators and fix the loose screw that keeps them from shifting. Fix the screw to re-engage the linkage and then re-sync them as you described in your first post.
I will try switching the temp from 60 to 90 when I go to work today. I didnt change the aux heat pump. I did feel both hoses on it and they were hot so I assumed it was flowing through. Although I was just guessing. Is there a way to test the aux. heater pump? I did see the posts for fixing that screw. Is there any way to know they are the problem before I go tearing all that stuff out or do you just have kinda guess at this one? I read every post I could find relating to no heat. I didnt think it was the actuators cause that seemed to be the fix for the one side is hot and the other is cold problem. Thanks for the input
 

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Discussion Starter #4
Well switching from 60 - 90 degrees doesnt cause it to blow warm. But when I start the car it blows warm for a split second. I wonder if its the same issue with the actuators.
 

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1997 Catera
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172 Posts
I would check the vacuum line on the heater control valve (pull it off at 60 and again at 90 to see if vacuum applied / not applied); maybe the HCV is stuck? Swap the two lines on the RH side and see if that makes it hot.

I don't think the actuators will cause the hot-then-cold effect. Both would have to be off at the same amount. I agree on that one.

I'll have to dig later for a quick test for that heater aux pump.
 

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Discussion Starter #6 (Edited)
ok, I'll give that a shot when my wife gets home in a couple hours and report back. Thats behind the motor close to the fire wall on the pass. side right? It has a vaccum hose on the top and 2 coolant hoses on it. Thanks again
 

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Discussion Starter #7
Update- Looks like it may be my aux. heater water pump. Heres what I found under the hood today...













I'm ordering a new one today. Heres my question, Should I leave the connecter un-hooked so it wont leak anymore? Will that cause any problems?
 

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314 Posts
Wow....! looks like you need a new connector also. Makes me want to check mine now. Where did you find this? I would say just leave it plugged in untill you're ready to replace it. I can't say what would happen if you did keep it disconnected but you're not going to have any more problems than you have now leaving it as is.
 

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Discussion Starter #9
Wow....! looks like you need a new connector also. Makes me want to check mine now. Where did you find this? I would say just leave it plugged in untill you're ready to replace it. I can't say what would happen if you did keep it disconnected but you're not going to have any more problems than you have now leaving it as is.
The connector cleaned up good as new fortunately. The Aux. water pump for the heater (Theres one for the radiator also.) is on the pass. side fender under the reserve tank. It sits sideways. FYI, the part number or both auxiliary water pumps is the same. I plugged it back in for tonight. Should have the new one tomorrow. Thank goodness its an easy fix.
 

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1997 Catera
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I can't say what would happen if you did keep it disconnected but you're not going to have any more problems than you have now leaving it as is.
uh...I would leave it DISCONNECTED. Water (or antifreeze) in an electrical connector is a blown fuse (or worse) waiting to happen. You know it can't be working right so unplug it and prevent any damage to the circuit.
 

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Discussion Starter #11
ok I changed the pump but I still have very low heat. Again, its blowing about 80 degrees. I assume everyone elses blows hotter? Maybe it isnt supposed to blow hotter than that and it isnt really broken. My next step I guess would be the actuators maybe? Any opinions? Thanks.
 
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