AC/secondary cooling fan question

[secondchance]

Guys,

As we all know, secondary cooling fan gets switched on when the coolant temp reaches a certain temp (in my case I am running Marc Heibeck chip so the fan kicks on at, I think, 208) or when the AC is turned on.
My secondary fan turns on when the coolant temp reaches 208 (power to the fan and fan relay is working) but AC on does not activate the fan.
Looking at the manual it shows an AC coolant fan switch. Could thid be the culprit? Is this one of those switches on the AC high pressure line in front of the AC condenser?

[Paul Workman]

Guys,

As we all know, secondary cooling fan gets switched on when the coolant temp reaches a certain temp (in my case I am running Marc Heibeck chip so the fan kicks on at, I think, 208) or when the AC is turned on.
My secondary fan turns on when the coolant temp reaches 208 (power to the fan and fan relay is working) but AC on does not activate the fan.
Looking at the manual it shows an AC coolant fan switch. Could thid be the culprit? Is this one of those switches on the AC high pressure line in front of the AC condenser?

But, do both fans come on when it reaches "208"? (I don't know, but it crossed my mind that after Marc modded the fan switch(es), could it be that the fan is no longer tied to the AC, far as switching on goes? And, as long as they both come on at 208, does it matter if the fan(s) don't come on with the A/C? Just askin...)

Paul

[secondchance]

I'll check but I am quite sure both fans are running at 208. Marc does not defeat secondary fan turn on w/ AC actuation. My current chip is based on earlier Marc's chip to compensate for larger displacement, porting, intake cam and secondary deletion.
If secondary fan is not turned on w/ AC actuation typically when stationary (like at thestop like) AC will blow warm air until secondary fan kicks in with ECM command by reaching 208.

[564crewdog]

I just had this issue...I troubleshot this problem by disconnecting the fan switch, turning on the car and both fans came on. (eliminating the fan relay) The potential issues for me boiled down to low freon or a bad switch, since my system is still R12, rolled the dice on the switch and the A/C runs like a champ now! The culprit was AC Delco part #15-2351 GM part #14078970...found it on eBay for $20. Hope this helps!
V/R
Rich

[secondchance]

I just had this issue...I troubleshot this problem by disconnecting the fan switch, turning on the car and both fans came on. (eliminating the fan relay) The potential issues for me boiled down to low freon or a bad switch, since my system is still R12, rolled the dice on the switch and the A/C runs like a champ now! The culprit was AC Delco part #15-2351 GM part #14078970...found it on eBay for $20. Hope this helps!
V/R
Rich

I saw your post and looked up AC Delco part #15-2351 GM part #14078970. Problem is these are listed as ZR-1 part from 1990-1993 and my Z is a 94. I turned to Marc Heibeck and he will be sending me a part number for 94 (hope he remembers mine is a 94).

[secondchance]

It seems high pressure fan switch was changed starting with 94 model year, perhaps concurrent with change to 134a. GM 10223909 (AC DELCO 15-2878) is NLA.
I found a company that sells generic high pressure switches with various fittings, pins and pressure settings. Anyone know high pressure (close) and low pressure (open) settings for our cars?

[564crewdog]

If you want to stay original...

http://m.ebay.com/itm/301163238205?nav=SEARCH

[secondchance]

If you want to stay original...

http://m.ebay.com/itm/301163238205?nav=SEARCH

Incorrect one. This is ether compressor cut off or another one by the evaporator.
15-2878 has a red top w/ different plug.