No heat plaese help....

I just purchased a 1990 sc auto 35th a week ago. My temp gauge stays between the c/f halfway never overheats or drops below half but yet my heat only comes out hot every once and a great while. Other times its cold. My coolant light says low but not all the time. It also says change. I checked the levels they are filled to the top. I bought some anti freeze the kind thats says you can add to any vehicle I the filled my reserve half way since it was low. still no changes. I opened my radiator cap and it was full. Any suggestions will be appreciated. The car sat two years prior to driving .

get cooling system flushed. your core may be blocked. 2 years of sitting some of the scale in the engine may have been loose and the heater core acts like a filter (due to small openings) have it flushed and see what happens.

Back flush the the Heater core. Take off the heater hoses from and use a garden hose to back flush, opposite from the normal flow of the system.

Pull the sensor that goes into the coolant tank and clean the end of it with a small wire brush.....

The sensor ends get corroded and need to be cleaned....

tctc1981hotmail said:

I just purchased a 1990 sc auto 35th a week ago. My temp gauge stays between the c/f halfway never overheats or drops below half but yet my heat only comes out hot every once and a great while. Other times its cold. My coolant light says low but not all the time. It also says change. I checked the levels they are filled to the top. I bought some anti freeze the kind thats says you can add to any vehicle I the filled my reserve half way since it was low. still no changes. I opened my radiator cap and it was full. Any suggestions will be appreciated. The car sat two years prior to driving .

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TCTC I can see by your several posts that you're completely unfamiliar with a lot of the unique characteristics of these cars, and I suspect your're not really a mechanic. A lot of guys here are mechanics and are giving you feedback I think without realizing your limitations. So this isn't a "flame", but please take as much time as you can reading up here on a lot of the subjects you're asking about. If you look a the "related posts" at the bottom of thehse pages they''ll cover lots of ground pretty quickly. It will simply you help you understand your car better and it sounds like you want to accomplish that too. As far as your "change now" light, that's specifically for the oil and is loosely odometer driven, it should go off anywhere from every 2000-5000 miles depending on stop/starts and other factors the computer would analyze as hard or light service. It can be reset with a paper clip from the display panel. Poke clip into hole on panel, turn key to "on" but not "Crank". After a few seconds the "CHANGE" light will blink and then reset to "OK". The remove the clip.
I see you're also asking about fuel filter or pump, definitely follow the advice of those who say check the pressure at the valve on the rail FIRST. If there's no problem there, move on to the vacuum gauge. While the cars can be driven with the supercharger disconnected, performance is affected greatly. What I'd suggest at this point is also verifying that your bucking symptoms are NOT related to the supercharger and that it's really only a loose or holed hose. Then go after the heater problem. It's possible ALL one of these problems may be related to a common cause of something like a pump or the supercharger seizing up. By the way the advice about the coolant level sensor is right on, mine would show low if the tank overflowed and got the BOTTOM of the cap wet, you can see there's some electrical parts there and the insulating compound has deteriorated with time.
BE patient, hopefully you don't need the car as a daily driver. Hopefully it is unmodified as that simplifies all diagnostic procedures. I learned LOTS myself just by reading reading reading here.....and if you're actually handy with a wrench and DO follow some of the advice then you're gonna save a lot of money. ME, I admit, I pay other guys to do it but I still want to know how it's SUPPOSED to work. Good luck!

Thanks guys I'm new to the forum and also to the thunderbird. NOt to good with the wrench so I appreciate all the comments being made. I really love the car and want to keep it. But it looks like I better not sell my spare.

tctc1981hotmail said:

Thanks guys I'm new to the forum and also to the thunderbird. NOt to good with the wrench so I appreciate all the comments being made. I really love the car and want to keep it. But it looks like I better not sell my spare.

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The main point is that sometimes even the Ford service guys don't have access to the old service manuals anymore. I looked for someone who specialized in performance Fords and called 'em and asked a few questions. With knowledge you get from here you can start to discern if the shop really DOES know the car well enough to trust 'em with it. This was Ford's high-tech flagship in 1990 and they really are sweet when they're running right but there's lots of parts for them that are getting hard to find. Yeah keep your spare! I haven't gone one complete year without spending at least $500 and a couple of times over $2000. I bought it 6 years ago at 49,000mi for $5000, it was immaculate, but I've done plugs/wires twice, electronic shocks are $1200 installed, ABS is now like new, Cam Position sensor, belts, hoses, tires, transmission, battery, motor mounts, oilpan gasket (you have to lift the engine for that one), give me a few more minutes and I'll think of something else...oh yeah, it's time for new front rotors and pads. After that I think I may finally get a service free year out of her! I'll be into it for about $13,000 at 100,000mi, BUT I KNOW EXACTLY what I've got.
Also remember to take into account that the ABS and transmissions changed in '92 if I remember right so the year of your car is relevant in those categories when reading posts.
Finally if there's one name here whose posts I'll take to the bank it's Duffy Floyd. Dave Niebert and XR7Dave are really good also. Not to slight anybody else, I just remember finding stuff in their posts that helped me when I was learning about my car, which a is a '90 auto, mechanically identical to yours.

It is weird that your heater blows warm every once in a while. Here is an easy way to find out if your heater core is plugged without lifting a wrench or spending a dime. You have 2 coolant hoses that run to the firewall of the car. They are behind the inlet plenum which the throttlebody bolts to. look behind the inlet plenum to see them, they are kinda tough to get to. These coolant hoses connect directly to the heater core.

Now heres the fun part. Take the car out for a drive and get it all nice and warmed up. Don't even turn the heater on at all when driving. When you get back, shut the car off and reach your hand back to those two hoses and squeeze each one. If the heater core is plugged you will notice one of the hoses is much warmer than the other. If that is the case, have your heater core back flushed and cooling system flushed. In some cases, your heater might work ok for a bit but go back to the same tricks. If that is the case you will have to replace the heater core which is a big job on these cars.

Chris