Radiator Fans only working with A/C on

[Dynomite]

Originally Posted by Franke

Is there really a problem here? Based on what I read in the FSM, it looks like the primary fan should come on at 234 degrees F + if AC is off. Engine oil temp also factors into the fan request as well so if the temps are not as high as the FSM indicates there would be no fans request from ECM.
You indicate the you were able to figure out engine data from A/C system control screen to verify ECM knows engine temp to activate and it does know correct engine temps. Just curious if it met these FSM parameters?

Good question

Originally Posted by MrsMcNastys

Hi Guys,
Thermostat appears to be working correctly, with A/C off reached operating temp and no fans activate, temp hovered at mid gauge range at idle then slowly crept up higher.
Turn on A/C - both fans kick on, quickly brings temp down below half way, cycles on and off - can idle for hours no problem.
Turn A/C off - no fans, let the temp climb quite a bit one time to see if fan activation was delayed - still nothing.
Any suggestions would be greatly appreciated.
Ed

It is not known from the description exactly what the coolant temperature was in degrees F during the testing.

As an aside......... Marc Haibeck's Calibration AYBKG (1990) Turns both of the cooling fans on at 205 degrees F. Both turn off at 200 degrees F.

[XfireZ51]

I 'm looking at a stock 90 bin file AYBK, and it shows Fan 1 ON at 112C which sounds awful high for me. Fan 2 ON at 114C.

A stock 92 calibration w fans (see attached)

107C/112 under 12mph

112/114 over 12mph

If the cal is stock, you may be waiting a while for fans to turn on. The gauge at the middle is 100C and its non-linear

[WVZR-1]

Originally Posted by XfireZ51

A stock 92 calibration w fans (see attached)

107C/112 under 12mph

112/114 over 12mph

If the cal is stock, you may be waiting a while for fans to turn on. The gauge at the middle is 100C and its non-linear

See if you have any information on the '92 PROM BATL (16175910) - just acknowledge I'd like the thread to continue with the OP's problem but since you mentioned '92 I thought I'd ask.

[Dynomite]

Originally Posted by XfireZ51

I 'm looking at a stock 90 bin file AYBK, and it shows Fan 1 ON at 112C which sounds awful high for me. Fan 2 ON at 114C.

That IS high at 234 degrees F.....that is why a lot of us install Marc Haibeck's Calibration AYBKG (1990) Turns both of the cooling fans on at 205 degrees F. Both turn off at 200 degrees F.

I am thinking (and analog gauges are estimates) that 234 deg F is way up close to the cross hatch area.

The trouble of using the AC Fans ON to cool down the engine is simply that with AC on (unless you set the interior temperature low) the AC condenser increases the heat through the radiator (additional HOT air through the radiator raising coolant temperatures).

[XfireZ51]

Originally Posted by WVZR-1

See if you have any information on the '92 PROM BATL (16175910) - just acknowledge I'd like the thread to continue with the OP's problem but since you mentioned '92 I thought I'd ask.

I know that the 2 broadcast codes for 92 were AZZC and BPPA. Had not heard of a BATL.

[XfireZ51]

OK. Actually 3 bins for 92 AYWT, AZZC, and BPPA. All w the same values as the stock 92 bin I previously posted. 107/112, 112/114C

[WVZR-1]

Originally Posted by XfireZ51

I know that the 2 broadcast codes for 92 were AZZC and BPPA. Had not heard of a BATL.

BATL was a '92 only EXPORT PROM. I've got a few NOS and I was just curious. Thanks!

[XfireZ51]

Originally Posted by WVZR-1

BATL was a '92 only EXPORT PROM. I've got a few NOS and I was just curious. Thanks!

Ah! If you want to send it over I can do a compare.

[Franke]

Interesting info XfireZ51. 112Centi is 233 degrees farenheit and 114Centi is 237. I'm trying to understand why so high before fan request without AC. Is it possible maybe these bin values are modified somewhere else by other ECM inputs to lower the fan turn on request?

I have Marcs chip in my ECM and did see that the fans acted just as Dynomite says.

[WVZR-1]

So ideally if you had access to the CTS you would ground the primary fan relay to confirm operation and then supply the ECM with values from the CTS connector to match the Delphi published specifications.

Fan runs w/relay grounded (fan is OK), fan doesn't run when supplied the required resistance the assumed problem is internal to the ECM?

Here's Delphi specs for the GM 12146312 CTS:

http://www.pe-ltd.com/joomla/images/...olant_temp.pdf