Tweet
Some back story:
On the way home from SyTys@Carlisle 2025, I stopped for gas. After spending enormous amounts of my bank account in Bucees, I returned to my truck to find that the blower was no longer working. Of course, did the quick on-site test of flicking all the switches and levers. Still no blower motor, so I figured that with a truck that has nearly 200k on it, it gave up the ghost.
Got home, swapped out the original blower motor with a new unit. Still no blower motor. Further diagnosed the system by checking all the relays and doing jumpers. Finally found that the pigtail connector to the AC selector switch (the one that controls low, max, bi-lev, etc) had cooked a wire plus melted the connector. So, thanks to another owner, I was able to get the sub-harness section of the AC selector panel. I swapped out the melted connector and cooked wire and bought a new selector switch since one of the connection points was fried as well.
I figured now I had the issue fixed. But the AC clutch wasn't kicking on in certain settings, and the blower motor would run with the ignition on, but the AC was completely off. The only thing I could figure out was that it was the wrong selector switch. All of the parts stores listed 2 part numbers with no details on what the actual differences are between the switches. I did some digging and came to find out that basically most of the AC selector switches offered by the parts stores are MANUFACTURED INCORRECTLY, and people had similar working/not working scenarios after replacing their switch. These switches are $42 btw.
From an old forum thread, I saw someone had recommended the Four Seasons brand switch available from Rock Auto. So, another $40 later, I ordered it and got it swapped out with the now-known faulty-manufactured Duralast switch.
BACK TO NORMAL AND I HAVE AC AGAIN!
So, putting this info up for future reference in case anyone needs to replace their AC selector switch in the trucks. The ISTR website has also been updated on the part number page:
--
Adam
SyTyRegistry.com
Syclone #237
Sonoma GT #012
On the way home from SyTys@Carlisle 2025, I stopped for gas. After spending enormous amounts of my bank account in Bucees, I returned to my truck to find that the blower was no longer working. Of course, did the quick on-site test of flicking all the switches and levers. Still no blower motor, so I figured that with a truck that has nearly 200k on it, it gave up the ghost.
Got home, swapped out the original blower motor with a new unit. Still no blower motor. Further diagnosed the system by checking all the relays and doing jumpers. Finally found that the pigtail connector to the AC selector switch (the one that controls low, max, bi-lev, etc) had cooked a wire plus melted the connector. So, thanks to another owner, I was able to get the sub-harness section of the AC selector panel. I swapped out the melted connector and cooked wire and bought a new selector switch since one of the connection points was fried as well.
I figured now I had the issue fixed. But the AC clutch wasn't kicking on in certain settings, and the blower motor would run with the ignition on, but the AC was completely off. The only thing I could figure out was that it was the wrong selector switch. All of the parts stores listed 2 part numbers with no details on what the actual differences are between the switches. I did some digging and came to find out that basically most of the AC selector switches offered by the parts stores are MANUFACTURED INCORRECTLY, and people had similar working/not working scenarios after replacing their switch. These switches are $42 btw.
From an old forum thread, I saw someone had recommended the Four Seasons brand switch available from Rock Auto. So, another $40 later, I ordered it and got it swapped out with the now-known faulty-manufactured Duralast switch.
BACK TO NORMAL AND I HAVE AC AGAIN!
So, putting this info up for future reference in case anyone needs to replace their AC selector switch in the trucks. The ISTR website has also been updated on the part number page:
- A/C Selector Switch:
GM/AC Delco #15-71490 or #16047877
Four Seasons #36695
*NOTE – Replacement switches from the popular auto part stores have been known to be built with incorrect electronics, leading to faulty switches when new out of the box. Symptoms include settings not working altogether or items running when not selected. The GM/AC Delco and Four Season part numbers have been tested and proven to work correctly.
--
Adam
SyTyRegistry.com
Syclone #237
Sonoma GT #012