Potential Cooling Fan Problem - ZR-1 Net Registry Forums

eric · 05-25-2010

The aux. cooling fans on my 91 ZR-1 cycle ON at low speeds if the engine temperature begins to increase; however,

If I turn on the A/C compressor, the fans do not come on right away. I was under the impression that the auxilary cooling fans were supposed to come on when the A/C is turned on no matter what the engine temp.

Is this true? If so, I am wondering why mine do not come on along with the A/C compressor right away when the compressor is turned on.

Any insight is appreciated.

Thank you,
-Eric

tomtom72 · 05-25-2010

Eric, actually I do not believe it is a straight line from the A/C compressor turns "on" and the fans ( 1 & 2 ) are turned on.

Page 6B-5 lists these inputs as having influence on fan operation:
A/C condenser pressure, coolant temp, oil temperature, vehicle speed, TPS signal, rpms, and ECM status are all listed in the FSM as having an effect on fan operation.

I know if my coolant temp is up around 220+ and I'm stopped in traffic and I turn on the A/C the secondary fan comes on to join the primary. But if I turn on the A/C at idle in open loop ( cold coolant less than 140* ) neither fan runs.

Tom

GOLDCYLON · 05-25-2010

I have to agree with Tom here. On my 91 if the AC is turned on it's not an automatic secondary fan function. It takes the other perimeters to be met as indicated above. I think the direct secondary fan rumor applies to engines that already meet the temp perimeters then it's an immediate on.

05-25-2010	#1
eric Join Date: Mar 2010 Location: ARIZONA Posts: 5	Potential Cooling Fan Problem The aux. cooling fans on my 91 ZR-1 cycle ON at low speeds if the engine temperature begins to increase; however, If I turn on the A/C compressor, the fans do not come on right away. I was under the impression that the auxilary cooling fans were supposed to come on when the A/C is turned on no matter what the engine temp. Is this true? If so, I am wondering why mine do not come on along with the A/C compressor right away when the compressor is turned on. Any insight is appreciated. Thank you, -Eric

05-25-2010	#2
tomtom72 Join Date: Dec 2004 Location: Jacksonville, FL USA Posts: 4,645	Re: Potential Cooling Fan Problem Eric, actually I do not believe it is a straight line from the A/C compressor turns "on" and the fans ( 1 & 2 ) are turned on. Page 6B-5 lists these inputs as having influence on fan operation: A/C condenser pressure, coolant temp, oil temperature, vehicle speed, TPS signal, rpms, and ECM status are all listed in the FSM as having an effect on fan operation. I know if my coolant temp is up around 220+ and I'm stopped in traffic and I turn on the A/C the secondary fan comes on to join the primary. But if I turn on the A/C at idle in open loop ( cold coolant less than 140* ) neither fan runs. Tom __________________ 1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member

05-25-2010	#3
GOLDCYLON Join Date: May 2007 Location: Peoria, AZ Posts: 9,153	Re: Potential Cooling Fan Problem I have to agree with Tom here. On my 91 if the AC is turned on it's not an automatic secondary fan function. It takes the other perimeters to be met as indicated above. I think the direct secondary fan rumor applies to engines that already meet the temp perimeters then it's an immediate on. __________________ GOLDCYLON - 91 ZR-1 #2014 GOLDCYLON - 90 ZR-1 #2794, 4L60e (Formerly Schrade's) GOLDCYLON - 11 CTS-V Arizona State Director 91 WHITE/BLACK #2014. 380 P&P&PCed,Ported Heads, Jeal Long tubes, Corsa Exhaust/FIKSE FM-5s /LED TLs, LED Headlights, Front Wilwood 6 piston narrowlite calipers and rear Wilwood caliper street shop mod,CNCed Coolant Pipes,TPI Cvr,Filter cover,Stainless Bolts, DRM/DOM PROM /ZFDOC mod build #102,DRLs,BMAD with stainless Debris Screen,Coplan Air Blaster, Pioneer APP Radio 4,Brey-Krause HB,Sub Bar,Fire extinguisher seat mount,DRM Coilovers,LEDs everywhere,Compass mirror (orange),V1 DIC hidden display, Homelink sun visor, Carbon Fiber top x3 and APSIS Carbon Fiber interior, APSIS CF Steering Wheel/NAPA Leather, Banski trailing arms, Guldstrand front suspension,urethane bushings from Prothane (total suspension) ZFDoc drive shaft safety loop, raptor shift light (orange),AO engineering louver front plate, Console seat cushion, 96CE seats with black custom Sheepskins, ss billet catch can,Viper remote entry/alarm,Cragar Rear Louvers,LED side louver lights, Dewitts Radiator with SPAL fans and a Woods 160 T-Stat 90 RED/BLACK #2794. 4L60e Automatic Stage V by RPM Transmission, TCI Dedicated TCM, OBX Stainless Headers, Corsa Exhaust, SAN Secondaries and Haibeck PROM, Exotic Muscle Coil overs, LED Interior Lights, LED Tail Lights, LED Headlights, 94 Sport seats with black custom Sheepskins , Cragar rear louvers, GS Front calipers, Banski Trailing arms, APSIS Carbon Fiber steering wheel, Front and Rear Baer Eradispeeds, DRLs, Guldstrand front suspension,urethane bushings from Prothane (total suspension), Dewitt's Raditor with Dual SPAL fans and a Haibeck 170 T-Stat 11 RED/GREY CTS-V