alrosenzweig

I have a 1990 totally rebuilt....actually orig block gone built up all new everything....with 4 bolt main. been running real good still does.
Let idle in garage ran with AC on temp gauge hit the "danger zone" which is 260 or 255 ....the upper left (drivers side) radiator fan never comes on. Best guess on where or what my issue is? And or what to check first?

of note when I turn off AC temp will come down......this time in garage I just shut her down. By the way radiator is new.....the only thing that's orig is AC, Alt, starter and throttle body.

thank you for your answers. I have read many posts on this issue but see only 1 that I believe might be the answer....actually 3 LOL , fuseable link, temp sensor and a code in the ECM or CPM? the lower fan on the right passenger side if you will.....

Al

WVZR-1

Right side does what?

Does the left fan motor run when wired direct? Have you actually checked anything at all? If the motor doesn't run when wired direct that would seem to be maybe the problem. If it does then you actually start the various checks, GAUGES FUSE, B+ to the relay etc.

Do you have the FSM?

Churchkey

Left fan should turn on @ 228* coolant temp or whenever the AC is in use.
Right fan on a 90 model is controlled by AC high side pressure it will run when high side pressure exceeds +/- 190 lbs, it is independent of coolant temp.

When you get the left side coolant fan to work suggest connecting the fan relay ground wires together = both fans will run. Fan relays are together located @ the left side of the radiator shroud. Fan relays have 12V supply @ all times you can test relay & fan operation with ignition off.

See the 8A manual. 8A-31-0 for the fan wiring flow chart.

alrosenzweig

I have not wired anything.....I'm seeking help to decide where to start.....car runs great in 110 degree temp no problem.....at 60 mph with AC on no problem....at stop and go the lower right(passenger side) comes on cleanly when internal temp hits 160 or 180....not sure automatically comes on when hitting AUTO and turning temp to 60 on the in ? side climate control....this engages the override lower right fan Main. ? I'm told.....Soooooo I set it up on the blocks in the garage to see if and when the upper left (Drivers Side) would and Should come on and didn't.
I would just like to know where to look first. EVERYTHING IS NEW.

i appreciate you all

WVZR-1

Both I and Chuchkey mentioned the FSM. Do you have one?

Churchkey

Pierce the power wire to the left side fan a straight pin will work. Supply 12V to the pin with a jumper wire.
Fan works = proceed to the 90 model flow chart included here you have a switch or connection or 12V supply issue.

Fan does not work = If the ground for the fan is good replace the fan.

Copy this then rotate it to read or print it to read I don't have time to sort it.

BTW: Its 'preciate y'all

pdf.gif wiring coolant text.pdf (288.2 KB)
pdf.gif wiring coolant fans.pdf (314.4 KB)