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Followup To
Question -
Hello Roland! I saw an answer to a question that is similar to mine, but I thought I would write and ask anyway, just to be sure. I have had this 87 Chrysler 5th Avenue for a few years now, and every year I have trouble with the heater. The system will blow cold air (even when in heat mode) until the temperature outside reaches below zero. After it hits below zero, the heat will start working and will run good until springtime, when it will continue to blow hot air until it reaches a certain temperature (of which I'm not sure, never drive it that time of year).
I know that eventually the heater will work, do you have any suggestions to get the heat running BEFORE it gets that cold outside? I would appreciate any help you can give me. Thanks!
Answer -
Hi Crystal,
That car is a rear wheel drive model, correct? And which engine does it have (look in the upper corner of the underhood sticker for the size of the engine; and how many cylinders, please? The only explanations that I can give depend upon the answers to the above questions. But basically it could be if it has a 4 cyl engine that you have air trapped in the heater core so it doesn't pump water through. It is fairly simple to get rid of that and I can give you the procedure. The other possibility is that the heater by-pass valve is sticking open so that the coolant doesn't have an opportunity of even flowing thru the core. That is a valve whose purpose is the maximize the air conditioning function when you have the unit set to "max AC" by keeping the warm coolant out of the cabin entirely. The valve is under the hood and is a vacuum operated. It could be a sticky valve or a leak vacuum line that is not effective at closing the valve. I have info on the front wheel drive vehicles, but not the rear for '87, so I may not have the definitive answer for you but let me know if its front or rear drive and what the engine is and we'll go from there.
Roland
Hello Roland, thanks for your prompt response. It is indeed rear wheel drive, sorry, I didn't realize you were a front wheel drive specialist. My apologies. The engine is 5.2LV8 (318) and it's an 8 cyl. How would you go about fixing the valve issue? I remember someone mentioning that to me before as a possible cause, and it sounds plausable.
Would that have anything to do also with the fact that the temperature selection (it's just a little slider) doesn't really effect the temp of the air coming out? When it does come on, it comes on full blast hot or full blast cold. Trying to select a specific temp. with the temp. selection slider (I believe it's as high as it goes right now, 80F?) certainly doesn't select a specific temp.
Thanks for your help, even considering this isn't exactly your field of expertise, your suggestions have still been helpful.
-Crystal
AnswerHi Crystal,
In you last question you gave me a tip that this system may be caller a semi-automatic temperature control system. If that is so (the temperature scale with numerical values is the clue, max reading of 85 degrees) then we have an entirely different set of considerations. Do you have a reliable mechanic who likes to take on new assigments, or a dealership that has handled Chrysler cars since the mid-80's with a mechanic who is knowledgeable about the AC/heater system of your car?
I can offer to copy the xerox pages from the '83 shop manual that describes the entire system and how to test and service it. The system is probably unchanged in your '87. Giving advice at a distance is not really practical. So if you want me to do that, I'll copy the 20 pages and postal mail them to you. It will cost about $2.00 to do that and you can mail me back some postal stamps in that amount when you get the copies.
So if you want to go that route, email me your postal mailing address.
