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Hi, I have a 1988 Trans Am with digital dash at electronic air conditioning controls. Recently high speed quit working on the blower. I replaced the switch with another good switch to tested and high-speed still does not work. Before it went out to it didn't seem like it was putting out much here even though it appeared to be running at full speed. I am assuming this is a blower motor issue? Or is there a fuse somewhere for only the high-speed?
There is a resistor pack in the top of the hvac box under the hood, and a high speed relay by the fan motor that you should check out. Lack of high speed is a good indicator the relay might be malfunctioning.
There is a resistor pack in the top of the hvac box under the hood, and a high speed relay by the fan motor that you should check out. Lack of high speed is a good indicator the relay might be malfunctioning.
Thanks Drew,I am new to third gen problems. Any chance you may have photos of the relay and resistor location? I don't have a service manual yet. I bought a factory one online but it hasn't shown yet
Yes, I believe so. I'd suspect the relay first if it's just High Speed that isn't working, shouldn't even take the resistor pack into account if I remember correctly. Check for battery voltage there, and maybe check that the coil wire is also getting power when the fan switch is set to High with a vent selected. The relay may have a pinout printed on it, otherwise we can help look up wire colors if needed.
Yes, I believe so. I'd suspect the relay first if it's just High Speed that isn't working, shouldn't even take the resistor pack into account if I remember correctly. Check for battery voltage there, and maybe check that the coil wire is also getting power when the fan switch is set to High with a vent selected. The relay may have a pinout printed on it, otherwise we can help look up wire colors if needed.
IIRC the High Speed Relay used in the digital dash GTA cars was specific to those cars.
Mine is a Trans Am with digital dash,but I am sure it's the same as the gta setup.
Anyone know what the part number is then for the digital dash specific one? Are both of the relays fan relays on the digital dash cars? Mine has two.
You can bypass the relay briefly to test the theory that the relay is faulty. Or test the relay, by powering the coil side and checking the switched pair of wires for continuity. Not really any reason to throw a part at something so easy to isolate and diagnose.
You can bypass the relay briefly to test the theory that the relay is faulty. Or test the relay, by powering the coil side and checking the switched pair of wires for continuity. Not really any reason to throw a part at something so easy to isolate and diagnose.
Went to Autozone and got the relay. Forgot the old one and left it in the garage. Got it home and noticed the pin layout is reveresed so it won't work. Now I have to bring it back this morning.
All this kind of needless crap is another reason I love 50's and 60's cars. Honestly,these are beautiful cars,but I am not a fan of the 80's technology with relays for this and computer controlled that and Check engine lights and sensors that fail and having to have electronic diagnostic equipment.
I had an 82 Trans Am before and that was what I actually wanted again,but was unable to find one,probably due in part to the fact that it was the same car use the knight rider and they are now sought after for conversions. I really liked this car and the fact it had the digital dash which reminded me of KITT.
Anyway,forgive my venting. I was able to replace my climate control module yesterday and fix that one problem.
Last edited by JimRockford; 04-07-2017 at 10:01 AM.
Ok,well I pulled out the little relay and noticed now the blower motor doesn't work at all on any speeds. Wouldn't that indicate that the relay wasn't bad since before it worked on everything except high speed? What does the second or longer relay on the right next to the smaller relay do? The one I disconnected is he smaller one on the left. Does this sound like a resistor problem
Relay switches between the resistor and the full battery voltage as source, so it makes sense that none of the speeds would work. Now I'm not exactly sure what the differences are between the digital dash and the regular version though, would be helpful to have a wiring diagram for it. I can't say for sure which wire colors are what with the digital dash, so I'm not sure which ones to tell you to jump.
EDIT: Found some wiring diagrams here https://www.thirdgen.org/forums/elec...ml#post5698880
What are the colors going to the little relay? It looks like that might be the low blower relay and the bigger one might be the high speed relay. Removing either relay will cause all speeds to not work.
Last edited by someone972; 04-07-2017 at 12:14 PM.
It looks like (based on the wire colors) the bigger relay on the right controls the switching between the battery voltage and the resistor bank as the source for the fan. The smaller relay seems to control power going to both the resistor bank, and the power used to energize the coil for the high speed relay. If that's true you should be able to measure the red wire on the big relay and see battery voltage, and jumping it to one of the purple looking wires should run the fan. It looks like the positive input to the fan is some sort of pinkish color? You should be able to do an ohm check between the wires with the relay off and verify that that is the proper wire.
It looks like (based on the wire colors) the bigger relay on the right controls the switching between the battery voltage and the resistor bank as the source for the fan. The smaller relay seems to control power going to both the resistor bank, and the power used to energize the coil for the high speed relay. If that's true you should be able to measure the red wire on the big relay and see battery voltage, and jumping it to one of the purple looking wires should run the fan. It looks like the positive input to the fan is some sort of pinkish color? You should be able to do an ohm check between the wires with the relay off and verify that that is the proper wire.
So neither of those relays is the high-speed fan relay then?
I knew I had those diagrams and when I saw 'Rockford' update this thread just now I was gonna' log in and post them up. Thanx for finding them someone972!
Here are the wiring schematics for the 88 GTA Electric( digital dash ) Heater/Blower....
The big one would be what is known as the high speed fan relay.
Thanks. I've been to three auto parts stores and. I nobody has it in the computer. Now I can bring the darn relay now that I know what one it is.
I can't wait until my Service manual arrives
I knew I had those diagrams and when I saw 'Rockford' update this thread just now I was gonna' log in and post them up. Thanx for finding them someone972!
Thanks John in RI! I bought a service manual online and it hasn't come yet so this helps a great deal. Thanks
By the way John,those digital Camaro Berlinettas are amazing. I'm surprised Chevy beat Pontiac to a digital dash in the f body cars. It would seem more logical that Pontiac would get it first in the Trans Am since Knight Rider was so popular and KITT was a Trans Am. I believe the first digital dash Trans Am was in 1985
One more question if I may. Do these blower motors become "weak" over the years and run slow and draw more amperage? Is that what causes the relay to fail?
I can't find this relay at any auto parts store. None of their computers shown anything that looks like the large one off the right. Even rock auto only shows the smaller style relay,which isn't the high speed fan relay
Problem is not likely to be the relay itself. They don't go bad all that often.
Instead, observe the relay's wiring. Note that there is a large fat red wire. Follow that wire toward the driver's side of the car. Right about at the pass side valve cover, near the hose nipples on the heater core, you will come to a connector with the red wire, acoupla green wires, and maybe a black wire in it. (C115 on that schematic) Attempt to disconnect it: you will find that the red wire is BURNT TO ASHES inside it.
Cut the red wires off from it. Put a set of the BIG FAT THICK HEAVY-DUTY yellow slide terminals on them, preferably insulated ones. Not, the little thin narrow weenie yellow slide terminals that are the same as the red and blue ones except yellow; use only the BIG FAT THICK HEAVY-DUTY ones. If you can't get insulated ones, tape it over real good after you finish, to keep water out. Similarly, if there's a black wire in the connector, cut the side off that leads toward the blower motor, put a nice heavy ring connector on it, and ground it under one of the screws on the firewall, preferably where the ground strap already goes. (that being a hole and hardware already designed for solid electrical grounding) In other words, ELIMINATE that connector from the high-current path of the blower motor ENTIRELY. You can leave the green wires in it, they go to the AC compressor and the current there is low enough that those hardly ever burn up.
Last edited by sofakingdom; 04-08-2017 at 07:18 AM.
Right: somewhat like that, except that's the little weenie kind that's just like the red & blue ones except it has a yellow sleeve (for larger wire), but what you want instead is the BIG FAT WIDE HEAVY-DUTY kind.
Ok,replaced the high speed relay and it didn't fix the problem. Still no high speed. I have tried to locate the connector I was told about, the one that's on the driver side of the firewall. Is this it? If so it doesn't look burned to me
Last edited by JimRockford; 04-13-2017 at 10:36 AM.
Thanks,I followed the red wire and solved the problem. What stumped me is that on my car (88 t/a digital dash) the connector doesn't look like the one shown in your post. My connector is grey and has one wire,the red one,running through it. I wiggled it and the fan started up so I will be replacing the connector tomorrow. Here is a photo of what my connector looks like.
Last edited by JimRockford; 04-14-2017 at 06:26 PM.
Interesting... exactly the same, except different.
Once you get it apart, you'll see that the lazy GM engineering staff's summer co-op intern's sophomore project, actually contained the STOOOOOOOPIDEST possible thing that can be done in connector design: the junior intern thought it was A Good Idea somehow, to use the THERMOPLASTIC connector to hold the contact tension. There are no words that can describe how BAD of a screw-up this is. A new level of Hell needs to be invented just to hold "engineers" that make mistakes - no, I'm sorry, it's worse than that - that EFFFF UP that bad, and cash the paycheck anyway without sufficient guilt for them to open their veins at the bank teller's counter. The blackness of the soul leaves me speechless. I cannot conceive of how a person with that little conscience can NOT be on Death Row for some equally mindless crime of passion combined with momentary impulse and lack of self-respect. But who knows, maybe they are now.
At one time, about 10 GM vehicles from the late 70s through the early 90s were in the possession of my extended step-family, my brother, and my friends. (including my own) I repaired 7 of them that I can recall, for the EXACT SAME issue. Might have been more eventually.
You will also find the same dumbassitude under the dash: sooner or later, your ENTIRE HVAC system will cease functioning. At that point, it will be due to a similar connector that is the ONE point where power is supplied from the dash harness, to the HVAC harness. Replace that one the same way.
I agree,it's incompetent engineering,and inexcusable from the leader of the "big three". My other huge beef with the design is not adding an access panel for the fuel pump,and the temp at which these cars run and the fans kick on from the factory. The connector was so brittle that when I tried to *gently* separate it,it started crumbling.
Last edited by JimRockford; 04-14-2017 at 07:25 PM.
"You will also find the same dumbassitude under the dash: sooner or later, your ENTIRE HVAC system will cease functioning. At that point, it will be due to a similar connector that is the ONE point where power is supplied from the dash harness, to the HVAC harness. Replace that one the same way."
Thanks for giving me something else to look forward too! Lol.
To top off all this,the previous owner had taking the car to a "top rated mechanic" to have the ecm replaced and the idiot didn't put all the bolts back into the panels on the passenger side and I just noticed there is no air from the passenger side vent,but all the others have air. Whatever happened to "professionals" being PROFESSIONAL and doing their job carefully and correctly? The person deserves a dumbass award too. I shouldn't have to go in and fix things they should have done correctly in the first place. They just don't care. And I have the receipts for the work and if I told you what these guys charged you'd say they belong behind bars for rape.
Reviving old thread. I found this problem on my 1988 GTA. The car is completely stock and id like to retain the look. Although absurd I know Id like to find and replace this "melted" connector. Does anyone know where I could find one?
No idea. Regardless, you don't want to do that. Not unless you buy a shelf-full of em and you're prepared to replace em on a regular basis. Not the right way to handle the situation.
If you want to do something that looks stock, even if maybe it's stock for something else, get a Packard / Delphi / Aptiv 630 series connector set. You can get em at Mouser. You have to order about a dozen individual small parts, abuncha terminals, housings, seals, TPAs, CPAs, and whatnot; but if you get it right, it's IDENTICAL to what would come in some GM car. https://www.mouser.com/Connectors/Au...ors/_/N-1ehb5/
I've also seen somebody on ebay that specializes in connectors of about this age; might be possible to use some other connector for some other but closely related purpose, like for the main engine fan.
In a word, DON'T put back an exact duplicate of something that's lousy and inadequate, just to be "the same". Especially not for "appearance" given that (a) nobody else much cares, and (b) that eliminates the possibility of taking advantage of experience. Don't commit a hack job; but if you can improve something that broke because it was a POS to begin with, don't turn down the chance.
04-06-2017, 02:41 PM
