Randy_J

Anyone replaced the Therno-Fan switch that controls the rad fans from the TOP rather than from below? Advice?

The thermo fan switch on the 85.5 N/A failed - fans stayed on low with ignition off. Followed the Clarks Garage diagnostics and also did a relay swap, so I know it is the 92/102C thermo switch.

Is this a Porsche only part or did Audi and VW also use this switch? Thanks!

Vjgtrybno1

If you drop the fans, you can get there from the top pretty easily, just remember to reinstall the fans properly, seating them in the groove on the bottom BEFORE you screw in the three screws on top. Otherwise, you need to unscrew everything and start over. Ask me how I know that! A deep socket helps also.

There are some he-men who have replaced the switch without draining the radiator. Not me.

Todd157k

I didn't drain it. Took off the air box bracket and the top radiator hose. Deep socket on the thermo switch. New one on pretty easy. Added coolant, bleeding from the top screw as outlined on clarks. Whole job took about 45 mins. (with heating up the car checking it out)

UncleMaz

I just did this without taking off the top hose, just the airbox/front bracket. You need a 30mm deep socket and plenty of rags. Took less than 15 minutes. Have the other switch readily available to limit the coolant spill. Good luck.

UncleMaz

Oh, and a two inch socket extender helps.

Randy_J

Thanks gents! I thought it would be possible by removing the airbox and bracket - and thought it might be possible by removing the top rad hoses etc. Lots easier than coming from below. Gotta get a deep socket, but have lots of extensions and flex ratchet handles. I'll get a new thermo-switch this week. For now, I just rigged up a bypass switch to the terminals 1+3 in case the car runs warm with the AC on. Weather this week looks cool around here, so should not be a problem.

Thanks again for the fast replies!

R

schnellfahrer

I got to it from the top on my NA without removing anything. Popping up the headlights will help.

Randy_J

Hey guys, thanks for all the tips - easy to change from the top! All I had to do was remove the stock airbox (944 N/A) and without having to remove the fan shroud or anything else besides disconnecting the thermo-switch connector, a 1 1/8" short socket on a 2" extension did the trick. Easy to remove and install the new OEM part. Reconnect, and while the airbox was out of the way, check the DS grounds by the headlight, check coolant hoses etc. etc. I did not bother to drain the 1.5L of coolant ( I run water and Water Wetter anyway, so no anti-freeze went down the drain). Total time 45 minutes start to finish.


Much easier than raising the car and removing all the fan assembly etc from the bottom. Probably not as easy on the 951S, but then the next job is to pull that motor out and swap it with the 7,500 mile motor I bought last winter! I hear that comes out the bottom a lot easier though.

FRUNKenstein

Reviving an old post, but some info to add. Just spent a couple of hours last night replacing this switch on an '87 951. Thoughts:
1. Fan shroud & fans removal and replacement are definitely the hardest part of the job. It's not easy. Ended up GENTLY using a prybar to get the fan shroud back in - top left and bottom right corners are the sticking points.

2. You'll need to remove the bolt that secures the air conditioner line (that goes into the condenser) to the frame to get some slack to remove the fan shroud. Also, to get slack loosen but DON'T remove the 2 bolts that secure the air conditioner condenser to the frame. Removing doesn't really give any more slack than loosening them. Replacing the top bolt afterward proved impossible - I finally gave up after 30 minutes of trying to get it to thread.

3. I have a 4-post lift, but really wanted to get at it from the top. But, even after removing the airbox and raising the headlights, still a lot of plumbing in the way. After the fans were removed, very easy to reach from below.
If you remove the fans to get to it, you don't need a deep socket. I used a 1 1/8" combination wrench. Plenty of room with the fans removed.

4. Only spilled about a cup or so of coolant by having the new switch ready to immediately plug in. Did use a drain pan to catch that.

5. If you pulled the fan relay before replacement, don't forget to plug it back in before the test drive. Ask me how I know.

mpitt

Kc, do you think it's possible to do on the 951 from the top without removing much? I was hoping to do mine today on my lunch break since its finally nice out and I'm really hoping I don't need to raise it up and take a lot out. I keep looking in there and sighing when I think about it.

FRUNKenstein

Well, I think it is possible. I think removing the air box bracket and upper radiator hose might do the trick. For me, it was easier to just remove the airbox (bracket left in) which made it possible to remove the fan shroud. Once fan shroud and fans pulled out, getting to the switch was a breeze from underneath. But getting the fan shroud back in was a major PITA. Without a lift it would be worse. So, if you don't have a lift, I'd give it a shot from the top. But I don't think you could do it in less than 2 hours, so over a lunch break would be tough.