The OBS tahoe offered a condenser fan as an option from what I understand. I bought one of Amazon and bolted it up, but haven't wired it yet. Does anyone know how the factory wiring was for the condnser fan? If not, I will probably wire it so that the fan comes on with the AC compressor.
AC Condenser Fan Wiring
- Thread starter orange57
- Start date
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east302
Full Access Member
It was wired to a temperature sensor on the passenger side of the block, but I think it was more common to the 3/4 and 1-ton with the 454 or 6.5 diesel.
Anyways, I’ve read that temperatures over 200-something degrees triggered a relay to power the fan on.
Are the bolt holes already there on the Tahoe? Did you have to relocate the auxiliary transmission cooler?
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Anyways, I’ve read that temperatures over 200-something degrees triggered a relay to power the fan on.
Are the bolt holes already there on the Tahoe? Did you have to relocate the auxiliary transmission cooler?
Sent from my iPhone using Tapatalk
I thought that was for an electiric radiator fan, not just an AC condenser fan. After all, don't know that I see 200degrees too often, so the fan would never kick on. The purpose is to help the AC work better at idle, so I would think it would somehow be wired to the AC.
Didn't have to move the trans cooler, there were holes on the other side that the fan bolted right up to without issue.
Didn't have to move the trans cooler, there were holes on the other side that the fan bolted right up to without issue.
east302
Full Access Member
Here’s a link where some people offered more info on it. Some said it also came on when the compressor high pressure switch was tripped.
You’re right, having it come on due to coolant temperature seems counterintuitive if it’s supposed to improve air flow over the condenser at idle. Maybe GM thought of it as also helping the radiator when threatened with overheating.
Beats me...but I wouldn’t mind adding one.
https://www.gmt400.com/threads/normal-operation-for-aux-cooling-fan.42244/
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You’re right, having it come on due to coolant temperature seems counterintuitive if it’s supposed to improve air flow over the condenser at idle. Maybe GM thought of it as also helping the radiator when threatened with overheating.
Beats me...but I wouldn’t mind adding one.
https://www.gmt400.com/threads/normal-operation-for-aux-cooling-fan.42244/
Sent from my iPhone using Tapatalk
Thanks east. That looked like it was something with an auxiliary cooling fan on a 7.4L. I think what I am going to do is set up the fan to run when the compressor is engaged, but it switch on with a time delay relay, like 30 seconds or so. I'll post back when I get into it and get it wired up. Definitely need it in AZ.
RED TAHOE LS
Full Access Member
In a conversation a few days back about this same issue with east302, I explained that this was an issue with these OBS when they were new, generating the need for later models with being installed when factory assembled.
My Tahoe is all original 205k and still has all the factory AC. As you can see with the below pics, you cannot ask an AC system to cool any better than 38 degree range on low blow @ cruising speed. I too have the issue after 10-15 minutes idling with the dogs eating fast food, the cooling will creep up in the mid 40 range. Speeding up the idle will bring it back down but that's not an option. The CLUTCH fan was designed to operate off temperature rise to tighten up and roar like a lion (normal).
There is simply not enough AIR FLOW through the condenser as well as the radiator which transfers heat as well while in traffic or idling condition.
Please supply the items you purchased including pigtail and the option you choose to wire the fan. You will greatly supply some great information to the OBS Tahoe's left. Thanks for a great article.
David g...…...
My Tahoe is all original 205k and still has all the factory AC. As you can see with the below pics, you cannot ask an AC system to cool any better than 38 degree range on low blow @ cruising speed. I too have the issue after 10-15 minutes idling with the dogs eating fast food, the cooling will creep up in the mid 40 range. Speeding up the idle will bring it back down but that's not an option. The CLUTCH fan was designed to operate off temperature rise to tighten up and roar like a lion (normal).
There is simply not enough AIR FLOW through the condenser as well as the radiator which transfers heat as well while in traffic or idling condition.
Please supply the items you purchased including pigtail and the option you choose to wire the fan. You will greatly supply some great information to the OBS Tahoe's left. Thanks for a great article.
David g...…...
RED TAHOE LS
Full Access Member
This is a follow up to the above post. Today while on the way to town, I stopped @ the local DQ in the shade. This is to show how much effect ambient temperature can and will have on AC cooling. In the above post, the OS temperature was right @ 100, and the AC was just under 40 degrees, today you can see the OS temperature was 92, and the Tahoe was idling on low blower speed (the lower blower speed let's the evaporator cool more effective) and I'm sure my Robinair gauge is probably a little off (maybe 2 degrees + or - because it's close to 20 yrs old, but the best AC tools you can buy. My point, todays gauge showing just above 32 degrees compared to last week reading in 100 degree heat as comparison.
David g....
David g....
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