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Discussion Starter · #1 ·
Hi all!! Been reading this forum since I decided to take the leap and purchase an 03 95 LPT linear. The problem I'm having is that I have no heat once I get going on the highway. It seems like I have it when driving around slowly locally. I had a the bypass valve start to leak about 2 months ago and I pulled it, ordered a new one and epoxied the old one to stop the leak and just havent had the time to replace it with the new one. Could the bad valve be the cause of the no heat condition? Also, the first cold morning here about a week ago when I was driving to work and I noticed cold air coming out of the vents, I "lost" the temp gauge. This has happened twice but not in about a week.Any idea what can be causing this?? Thanks in advance and great info from all of you on the site!!
Andy.
 

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9-5's have a very sophisticated HVAC system....

The HVAC system in our cars will not deliver any heat to the cabin until the engine is warm. (This drives my wife nuts but I think it is great - guess which one of us is trained as an HVAC engineer!).

I believe your statement "I lost my coolant gage" is the key. A faulty engine coolant temperature sensor will cause the HVAC system to think the engine is not yet warm, and therefore not even try to deliver heat to the cabin. This same faulty sensor will result in eroneous temperature gage readings.

I think you will need to replace the engine coolant temperature sensor. Not too expensive, not too difficult, with a small reputation of being a failure item.

And "YES", a bad by-pass valve will cause problems too. Replace that first, then see if your problem is gone before you do the temp sensor.
 

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Discussion Starter · #5 ·
I'm hoping its the bypass valve..I already have it:D . Just tried a little experiment on my way home today. I put the ACC on high, let the car warm up about 5 minutes and drove the 4 miles or so to the highway. Had full heat. As soon as I got on the highway and hit cruising speed I could feel it getting cooler until she was blowing cold air full blast. Luckily here in New york its like late summer again and I wont need the heat again for a few days so I'll have to fix it before we get cold. I'll keep everyone posted after I change the valve this weekend (after work, I'm working both days:x ). If anyone else has suggestions let me know.
 

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Sth definitely wrong. If temp sensor says the HVAC that the engine is cold, the HVAC won't blow until the engine warms up (so, no heat). But it will NOT blow cold air instead! If the air goes from hot to cold and fan/distribution blows the same, I doubt it's the engine temp (or coolant temp) sensor. My money is on BPV.
 

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Discussion Starter · #7 ·
Thats what I'm hoping for. Coming home the temp gauge stayed in the middle the whole time. The funny thing about the temp gauge thing is that in the three times it has happened, if I shut the car off and started it up again, the gauge would read normal. Maybe the sensor is going bad as well, who knows!! again, everyone thanks for the input!!
 

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I had similar problems without the bypass valve leak.

My thermostat died this summer and had to be replaced. Since then, car warms up quick, doesn't blow cold air(unless i want it too) and the temp guage has never suddenly dropped to the cold mark when warming up.

Indie thinks that the thermostat was probably only opening part way. Enough that the engine would not over heat, but not enough to have a good supply thru the heater. The colder air when driving would just blow right thru the heater.
Have you tried switching from fresh air to recircular? I'd get a little warm air that way.

Good luck, hope it's the bypass valve so no more costs.:D
 

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Discussion Starter · #9 ·
I think its fixed!!!

Well changed out the BPV yesterday ( it only took me half an hour and I'm no mechanic:) . Amazing how quick it is to do when you've done it once before). And as of my drive in to work this morning, I have heat!!!. Its a good thing too because its supposed to get chilly here later in the week. Anyway, thanks to all for the input and I'll just keep reading until the next mechanical gremlin shows up that I cant figure out. Thanks again!!!
 
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