Hi everyone,
New member here. Just bought a 1988 Seville with just 57k miles.Bought it in San Diego and drove it home, a 150 mile trip.Apparently it has been sitting for a while but it ran just nicely except for the climate control. Everything worked but the heater. No heat,nada. That's the first problem. The second is the little yellow light (engine control system) went on when I restarted it after getting it home and won't go out. If anyone can offer any suggestions as to what I can try to fix these issues I won't have to drive it back and I would be grateful to you guys. It was a private party deal and I can do some repairs myself but I know very little about this marque but I had to have it when I saw the mileage and general condition of this car. You will see what I mean when I detail it and take some photos. Any help is really appreciated.

skyzzics

 

You need to retrieve the fault codes from the computer system. Check for a sticky on this web site on a tutorial to retrieve codes or do a GOOGLE search foranthony haukap. then click on his Cadillac web site. Pull the glove box liner and verify the blend door rod moves to open the heater door. Go from 60 degrees displayed to 90 degrees and with car running, verify the rod moves the door fully closed to fully open then post back.

 

Thank you carnut. Fault code retrieval is fun. And I removed the glove box and watched the rod move as instructed. Still no heat. I'm thinking maybe a plugged heater core? Are there sensors or relays to check?

 

could be a possibly bad heater core but check your coolant level to make sure its full if you dont have enough in that will cause it to still blow out cooler air. If you have the right amount of coolant in than see if you can back flush the heaer core by either removing the heatercore or disconecting both hoses that go into the firewall and then use a hose to flush it out an see if anything comes out. some times by doing this it will help out and your heater may work since i have done this to my 92 deville and found somebody had used stopleak and when back flushing it that crap came out. Good luck let us know what happens.

 

No sensors are faulty if the blend door moves, back flush the system.

 

You guys are awesome. I drained the coolant, disconnected the three hoses near the firewall (connected to each other by a metal tee) and rammed a garden hose in each until water ran freely.A little whoosh and a gurgle and out came some sediment that may have been stuck in the heater core for a long time.I bet the heater hasn't worked for years being that the car came from San Diego and it never really gets cold there.But up in the desert where I live it gets really hot in summer and just about freezing in winter so I like the heater to work. Thank you very much.
Just a few more little issues and I will have a 90 point concours car to tool around in. Example: antenna won't move, driver's seat is loose, front spoiler is hanging a little low, stuff like that. Photos to come soon.

 

does this car have the 4.5L v8? I have a 90 Seville with the 4.5L and I have driven it for well over a year with a 160 degree thermostat and I don't suffer from poor gas mileage, it purrs like a kitten. These motors are great. I learned that when city driving, if you keep the front defroster ON, it automatically starts the engine cooling fans. The engine will get warm on mine without the front defrost on, and it will cause the service engine soon light to come on. I am willing to bet that's the cause. If I were you I would run that engine cool, with a 160 thermostat. I have had great results with it in mine, and dont' have to worry about overheating and ruining the seals causing oil leaks etc.

You can clear the codes in the driver information centre, it will go away. You can jot down the codes as they appear and work towards fixing any potentially serious ones. You press OFF and warmer at the same time with the engine off and the key in the on position. (if I remember right, lol)

 

Yes, this car has the 4.5l engine and so far in my limited experience with it I am getting about 17-18 city and 25 or so at 70-75mph.I can live with that.
I'll try to remember that defrost trick this summer when the temps hit over 100 but I do not believe going to a 160 thermostat will make much difference in the desert most of the year. We will see.
I have learned to ignore the warning lights. I have been more concerned with checking batt volts and other stuff like tires. There's firestones on the front and although they have plenty of tread I just do not trust them. Also the rims are 14 inch and I am not comfortable with thateither. Anyone have suggestions as to tire brand and type to run for an aggressive driver in a location that has no snow and very little rain?I will hit the local yard to see what otherchanges I can make.Is it true that if I upgrade to an aftermarket sound unit that I will mess up the computer? I dumped most of my cassettes years ago. Radio reception sounds good though.

 

the reason whythe fans kick on when using the defroster is because no matter if it is blowing hot or cold it uses the a/c. so if you use the a/c in the summer any ways it will cause both fans to come on only because by using the a/c it causes more of a load on the engine and will cause the engine to run hot if the fan didnt kick on. What you should do is flush the coolant system to get rid of any debris and bad coolant and see where that gets you. any debris or slugdy coolant will cause you to lose 15% or more cooling efficency which can cause the engine to run hotter than normal.

 

you can put an aftermarket deck in the car and it won't affect the computer. I had a factory bose in my seville and put in a pioneer. If it's the bose system the speakers use their own individual amplifiers and also run at 1ohm resistance, so basically you'd need the correct adapter for the deck, and it means you have to change the speakers and rewire the speakers. It cost me $ 500.00 to have mine installed, but if you can do it yourself even better. It can be done yourself with patience and time.