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Fri Nov 07, 2025 12:45 pm

Noticed today that my gauge was running higher than usual. Felt like maybe my low speed fan wasn’t kicking on. Could hear high speed kick on and off occasionally in city driving.

Is it correct that, the low speed should _always_ kick on if the AC is running?

I haven’t had a chance to pull the grill off and do a test by shorting the connector but did run the van with AC and the fan did not kick on.

Got coolant. Have a good radiator. Oil is right. Engine is healthy. No liquids being lost. Suspect the fan currently.

Thanks

Fri Nov 07, 2025 1:33 pm

Correct!

Fri Nov 07, 2025 1:48 pm

Icebox500 wrote: Suspect the fan currently.

Thanks

Would the slow speed fan come on with the AC even if the fan switch that's screwed into the radiator is faulty?

When I first got my van only the high speed fan would turn on because the switch was either bad or the wrong version (I forget). However, my AC has worked.

I'm not sure but it might just be the switch and not the fan. Someone will correct me if that's wrong.

Fri Nov 07, 2025 1:52 pm

ALIKA T3 wrote: Correct!

Thanks!

Fri Nov 07, 2025 1:53 pm

Not sure I follow, nor have I done any digging in yet.

I will be poking at the system and testing it on Monday. Everything works great until it did’t, lol. I’m curious about the resistor.

James

SCM wrote: Icebox500 wrote: Suspect the fan currently.

Thanks

Would the slow speed fan come on with the AC even if the fan switch that's screwed into the radiator is faulty?

When I first got my van only the high speed fan would turn on because the switch was either bad or the wrong version (I forget). However, my AC has worked.

I'm not sure but it might just be the switch and not the fan. Someone will correct me if that's wrong.

Fri Nov 07, 2025 3:06 pm

I believe an 87 with factory air had a 3 speed radiator fan. Low, medium and no mistaking high.

Depending on how yours is wired might affect operation. Ours is configured to mimic factory ac fan operation.

Compressor engaged. Rad fan low
AC high pressure point reached. Rad Fan medium.

Coolant temp turns radiator fan on medium.

Coolant temp if exceeds desired coolant temp. Radiator fan on high. The factory also disabled the compressor when radiator fan was on high. This is for a 3 speed radiator fan.

There are earlier vanagons with 2 speed radiator fans.

Fri Nov 07, 2025 7:03 pm

Icebox500 wrote: Not sure I followquote]

my apologies for the missing word I meant to type.

My AC has never worked so that’s out of the equation for my personal experience. But, when my fan was only running on high speed it was due to a faulty fan switch-the one that screws into the radiator.

Fri Nov 07, 2025 8:16 pm

You need to short the wires going to the radiator fan switch to test for resistor function, that tests high and low. If it passes that test then it is likely the radiator fan switch that is bad.
IIRC you short the outer 2 and the high speed turns on, short one of the outer contacts to the inner turns on the low, one outer/inner combination will do nothing.

Sat Nov 08, 2025 8:27 am

Thanks all, very helpful and in line with what I’d read. Easy enough to test and something I can jump Monday.

If I have more questions and/or resolve the issue, I will post here!

Tue Nov 11, 2025 10:35 am

Pulled the old resistor finally (was too dang cold and windy yesterday). Ran some DMM tests - don't know the exact test or spec but got OL across any combination of connection testing.

Ordered a new one. Let's see what happens next!

She looks pretty tired.

Tue Nov 11, 2025 11:01 am

Did you run this test?

syncrodoka wrote: You need to short the wires going to the radiator fan switch to test for resistor function, that tests high and low. If it passes that test then it is likely the radiator fan switch that is bad.
IIRC you short the outer 2 and the high speed turns on, short one of the outer contacts to the inner turns on the low, one outer/inner combination will do nothing.

I had your same issue and when I jumped the fan switch the fan operated fine so the resistor was OK. A new fan switch and all is well.

Tue Nov 11, 2025 11:38 am

Sometimes I’m not as smart as I think I am so check my thinking here. I did jump the wires in various combinations, and I was not able to force the fan to come on. Prior to removing the resistor I was getting a high fan when driving. I did not get the low fan when I turned on the AC.

dobryan wrote: Did you run this test?

syncrodoka wrote: You need to short the wires going to the radiator fan switch to test for resistor function, that tests high and low. If it passes that test then it is likely the radiator fan switch that is bad.
IIRC you short the outer 2 and the high speed turns on, short one of the outer contacts to the inner turns on the low, one outer/inner combination will do nothing.

I had your same issue and when I jumped the fan switch the fan operated fine so the resistor was OK. A new fan switch and all is well.

Tue Nov 11, 2025 12:14 pm

If you have a three speed system IIRC the fan comes on medium with A/C. Not controlled by the fan switch.

The fan switch mounted on the lower drivers side of the radiator turns the fan on low somewhere about 195 and on high maybe 207 or so.

If you jumped the fan switch properly and only got high speed then I'd replace the resistor.

Tue Nov 11, 2025 12:24 pm

Right on, thanks Dave. Part ordered.