circlegroup

I have a 1990 Coupe TPI. I was testing a new blower motor and I think I crossed the wires and blew the fuse. I have checked all of the fuses in the fuse panal all are good. I understand that there is a 5 amp fuse on the firewall under hood. I cannot seem to be able to find it, Does anyone have a Photo of where it is at or at least describe where I might find it.

SunCr

At some point, GM changed the location of the fuse and placed it in the box labeling it A/C MDL Fuse. Otherwise, look for it on the firewall between the Evaporator housing and the right valve cover. It's input wire is going to be the same color as the hot wire to the blower (allmost always purple) and it's output to the Programmer is generally orange.

That fuse, even if blown, may not be the problem - it only protects the circuit sending actual blower speed (voltage) back to the Programmer and usually if it opens all you get is max blower and it may even run with the engine off. You should make sure the blower module - on the Evaporator Case - has power. It will be the red wire and with the key on or off, it should have battery voltage. If it doesn't have power, it's either protected by a 10 amp fuse labled a/c blower or it's on a fusible link behind the battery - though sorting out a blown fusible link can be problematic - rarely do they "look" blown and there are usually 6 or 7 of them all stacked up against one another. If it does have power, check the blower input to the control module. It's a brown wire and at blower speed "1" it should have about 2.5 volts; at blower speed "10", about 6 volts. The output to the blower - purple - should have 4 volts at "1"; 12 volts at "10". If it has power and the input voltages (if it doesn't have the low input volts, repost), but no output voltages to the blower, then the module is probably shot, but as a final check, verify the ground - black. The module and the blower share this ground so check from the blower to the frame and the module to the frame

If you need a new module it's about 100 Bucks and since it's used across the line, a Caddy, Buick, Olds, Ponitiac or Chevy Dealer should have one or NAPA also shows it in their online catalog.

circlegroup

From what you have told me I think it is the module that I fried. I have checked voltage to the module and it is good (all I have is a test light) I tested the purple wire coming out and there is no Light. I have not checked the ground at module but I did check it at the blower and it checked good so if it has a common ground with module I assume that it is good also I will check ground at module before buying a new one. All of this started when I was trying to find out why there was low air speed coming from vents inside of car. Could this module help this out? I have a new blower motor which I was checking when this happened.


I just ran out and checked ground at module and it is good, Is it really that easy to fry this unit I only crossed wires for a few seconds?

SunCr

Module's have a fairly high failure rate. Verify that there is an input voltage on the brown wire. If it has that and it's powered up, there should be an output to the blower.

SunCr

PS: You should verify there isn't a short to ground in the power feed from the Module to the Blower. The Module sits between the Blower and the fuse so if you short the power feed, the Module takes the hit, not the fuse. Hate to see you blow a new Module, though it sounds as if it was bad to begin with. You might also want to purchase a DVM. A cheapo from Radio Shack should be good enough.

circlegroup

I have checked all the leads to module and they all seem fine. I am going to put in a new module today. I want to thank you for your help