The Cab seems to get pretty high temperature-wise while puttering around town recently in the weather we've been having. The temp gauge goes about 3/4 way up (but not higher). The A/C works fine and doesn't cycle, so A/C relay is fine.

Any thoughts?

 

The oil cooler fan has a resistor which burns out and leaves only high speed working. Low speed would normally start at about 8:00 oclock and high around 10:00. Let the temp rise while idling and listen for the fan to start at about 8. If it doesn,t and high speed fan starts later then that is the prpblem. The AC uses another of the same part in it,s 2 speed fan circuit . A common problem.

 

I have an extra new resistor laying around from the previous car (that one had A/C resistor die). But I want to make sure.

If I remember correctly, there's a way to jump the relay somewhere to have the fan always be on high speed. I'd like to try and confirm that the temp does not climb up in town that way.

 

Do the fan switch modification..here is the link to more details on what you are seeing:

http://www.pcarworkshop.com/index.ph...Oil_Cooler_Fan

Here is the procedure for adding a manual switch:

http://www.pcarworkshop.com/index.ph...verride_Switch

I like the manual switch, it works really well, especially in hot weather. You can switch on the fan before the temp rises too much, therefore avoiding a peak.

High temps are an engine killer, so keeping the engine temp at 9:00 or below is key to a happy engine. John comments also sound correct, it sounds like your low speed circuit is also not working.

Cheers,

Mike

 

Mike, thanks! I just came back from reading the override DYI on your page a minute ago Might do that. Just wanted to confirm if there's a quick and dirty way to jumper something to constantly run high speed to check if temps stay down before doing the clean switch install.

Also, since I have the new resistor I should probably put it in anyway, eh?

 

Yes, you can do the shortcut and just pull the plug on the passenger side (pull the headlight). Instructions are on the site.

If that works, you can put in the resistor when you have time...perhaps when you are snowed in. :-)
Cheers,

Mike

 

Don't remind me of the white stuff, Mike Especially given that I'll be driving this 993 through teh winter like I did the previous 993.

I have to find details on the side as to which plug to pull to constantly run fan on high speed - not familiar with cooling circuits at this point.

 

It's the top one, can't miss it.

 

Tony, is it the one going to the resistor? If I pull it, what happens? the fan is always on and always high speed?

 

Yes, gently unplug it. The fan will always be on high once the ignition is on.

Let me see if I can find a pic...once the headlight is remove, look into the opening, you will see the black plug like in the middle of it...

 

Here's real simple explanation... https://rennlist.com/forums/993-foru...track-tip.html

 

OK, thanks a bunch, guys!

I've unplugged the connector behind the headlight. Turn the car on. The fan did not come on right away, but did so after 30-40 seconds. OK, turned the car off, re-plugged the connector, turned the car on... the fan came on, same speed (high speed, I assume). Odd.

Having said that, I've unplugged ut again and drove in the city for a while, stop and go with A/C on. The temp gauge stayed just under the 8 o'clock mark without going above at all. So I assume this solves the problem short term. Longer term would be replacing that resistor. Later on, possibly, putting ina switch just in case.