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Discussion Starter · #1 ·
A couple weeks ago, my AC mode selector switch (used to select MAX A/C, NORM A/C, HTR, etc.) grenaded itself behind the dash and made my AC unusable on a hot afternoon after work. So after a bit of frustration, I get the switch and all of its components removed from inside the dash. With the temperature selector cable removed and all wiring harnesses disconnected, I installed a new Standard Motor Products selector switch. It only goes in 1 way and can only connect to 1 lever that can only select 1 mode at a time. So I'm fairly certain I don't have it in wrong, and the wiring harness plugs in smoothly.

But, this is the issue I'm having:
When I select MAX A/C: The truck thinks it is in HTR mode with no compressor action, but the vent doors function like MAX AC
Norm AC: Normal AC vent mode, with NO compressor (truck thinks it is in vent mode)
BI-LEV: functions normally as it is the middle selection
Vent: Normal A/C compressor action with vent-only blower selection
HTR: Compressor cycles as if it's on MAX ac, but the fan only blows on your feet and at the windshield, as if it was actually on HTR.

BASICALLY, BOTTOM LINE: The vent doors open properly depending on the mode I select, but the AC modes are reversed??? Faulty switch or what? I'm scratching my head on this one but I don't want to order another switch if I'm just hooking something up wrong. I don't see how I could though.. I don't believe it's a vacuum leak either unless I could have possibly pulled one loose while messing with the cluster??? I thought the hoses were long enough as I only pulled the cluster out a maximum of 3 inches. Would an HVAC vacuum leak even cause an issue like this? I just need to know where to start, because having a max ac mode that only blows on your legs sucks. This is a really hard issue to explain and I would be totally open to posting a youtube video if you think you can help me but just don't quite get what's going on.
 

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Moved to Heating/Air Conditioning.
 

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Why doesn't that surprise me? Probably a Dorkman part.
 

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Discussion Starter · #6 ·
Update FYI it turns out the switch that both Autozone and orileys sells is not correct.
Hey man, sorry for not replying to your previous post. I got mine from standard mfg. and I guess it must be wrong too. Did you end up ordering another one that worked properly? If so what brand? It’s been really annoying to have half-a**ed AC for the last few months since MAX AC is no longer functional with the faulty switch. Glad you got to the bottom of it!
 

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Hey man, sorry for not replying to your previous post. I got mine from standard mfg. and I guess it must be wrong too. Did you end up ordering another one that worked properly? If so what brand? It’s been really annoying to have half-a**ed AC for the last few months since MAX AC is no longer functional with the faulty switch. Glad you got to the bottom of it!
I “repaired” my original switch for now but I ordered one on LMC I’ll let you know if it works correctly
 

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LMC isn't any better than anyone else when it comes to quality. They have a lot of offshore items.
 

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Update: LMC switch was backwards just like orileys and Autozone.
Can’t seem to find a new replacement That works correctly anywhere. Maybe the dealership but I doubt they still have parts for these trucks.
 

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Can you post a pic of the backside of both?
 

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A couple weeks ago, my AC mode selector switch (used to select MAX A/C, NORM A/C, HTR, etc.) grenaded itself behind the dash and made my AC unusable on a hot afternoon after work. So after a bit of frustration, I get the switch and all of its components removed from inside the dash. With the temperature selector cable removed and all wiring harnesses disconnected, I installed a new Standard Motor Products selector switch. It only goes in 1 way and can only connect to 1 lever that can only select 1 mode at a time. So I'm fairly certain I don't have it in wrong, and the wiring harness plugs in smoothly.

But, this is the issue I'm having:
When I select MAX A/C: The truck thinks it is in HTR mode with no compressor action, but the vent doors function like MAX AC
Norm AC: Normal AC vent mode, with NO compressor (truck thinks it is in vent mode)
BI-LEV: functions normally as it is the middle selection
Vent: Normal A/C compressor action with vent-only blower selection
HTR: Compressor cycles as if it's on MAX ac, but the fan only blows on your feet and at the windshield, as if it was actually on HTR.

BASICALLY, BOTTOM LINE: The vent doors open properly depending on the mode I select, but the AC modes are reversed??? Faulty switch or what? I'm scratching my head on this one but I don't want to order another switch if I'm just hooking something up wrong. I don't see how I could though.. I don't believe it's a vacuum leak either unless I could have possibly pulled one loose while messing with the cluster??? I thought the hoses were long enough as I only pulled the cluster out a maximum of 3 inches. Would an HVAC vacuum leak even cause an issue like this? I just need to know where to start, because having a max ac mode that only blows on your legs sucks. This is a really hard issue to explain and I would be totally open to posting a youtube video if you think you can help me but just don't quite get what's going on.
I'm experiencing the same problem on my 93 S10 Tahoe. Bought first switch from Autozone (Duralast SW3021) and it worked the way you described. Thinking bad switch Autozone replaced it. Same thing with that one. Bought another switch from Advanced Auto (BWD HS297) and same thing. They had no idea what to do with it. So I went to the dealership and they were of no help as to why this was happening except to tell me the switch is now unavailable. All the guys there were young and had no knowledge of the older S10 Blazers. AC Delco has a switch I found online (Part# 15-71490) but it listed for about a hundred bucks and I only saw one so I'm sure they're not easy to come by. I'm not sure I want to spend that much but I might have to.

I took the switch connector apart and moved the terminals around but had no success. I did manage to break the connector tab off so now I have that. I can get a/c blowing when the selector hits bi-level and vent and in AZ that's a priority. I get heat but hardly any airflow. I noticed the vacuum valve is rotating properly so the actuators are now not in sync with the switch functions I believe causing the restricted airflow. My next step is to get up under the dash and look at the vacuum harness and maybe I can swap the hoses around to different actuators to get the airflow more aligned with the switch. Wish me luck! I hope this info helps those who are having the same issue and will post my findings to report my results. Good luck!
 

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Discussion Starter · #13 ·
I'm experiencing the same problem on my 93 S10 Tahoe. Bought first switch from Autozone (Duralast SW3021) and it worked the way you described. Thinking bad switch Autozone replaced it. Same thing with that one. Bought another switch from Advanced Auto (BWD HS297) and same thing. They had no idea what to do with it. So I went to the dealership and they were of no help as to why this was happening except to tell me the switch is now unavailable. All the guys there were young and had no knowledge of the older S10 Blazers. AC Delco has a switch I found online (Part# 15-71490) but it listed for about a hundred bucks and I only saw one so I'm sure they're not easy to come by. I'm not sure I want to spend that much but I might have to.

I took the switch connector apart and moved the terminals around but had no success. I did manage to break the connector tab off so now I have that. I can get a/c blowing when the selector hits bi-level and vent and in AZ that's a priority. I get heat but hardly any airflow. I noticed the vacuum valve is rotating properly so the actuators are now not in sync with the switch functions I believe causing the restricted airflow. My next step is to get up under the dash and look at the vacuum harness and maybe I can swap the hoses around to different actuators to get the airflow more aligned with the switch. Wish me luck! I hope this info helps those who are having the same issue and will post my findings to report my results. Good luck!
I’ve been riding around with masking tape over my AC setting panel relabeled to match the aftermarket switch. Been like that since I put it in (over a year now). I figured since every other brand switch acts the same way, I’m SOL and have to make due. Getting behind that dash is TIGHT but if you manage to figure it out I might give it a shot. Good luck and get back with us because I’m probably not the only one that gave up trying to make it right.
 
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