I was using the A/C earlier today and again on my way to dinner tonight. After dinner I slided the central switch to vent, turned on the fan **** from position "0", depressed the A/C switch as usual, and drove off from the parking lot.

I usually left the fan at position 1 at night. While I was driving, I noticed no air was coming out from the vents. I turned the **** clockwise to position "2", then "3", and eventually "4", but still I got no airflow at all.

In fact, the fan motor did not even run regardless of any position. I did not hear the clutch engaged at the A/C compressor. However the headlights and foglights as well as all other electricals are operating okay.

What had happened to the unit? Where should I check first? Does anyone has similar experience with the HVAC unit. btw-heater is no longer work as well now. Is it possible the fuse has blown? The fuse panel has never been touched so I am going to undo it first thing tomorrow morning.
Any idea where to look? Thanks.

 

Try DEFROST - if the fan runs on DEFROST, but not on heat or A/C positions, replace the blower relay.

 

Check your fuse first. I have seen this one a few times esp on ceramic-style fuses. Happened to my '84 a few weeks ago.

Fuse might not even be blown - just try turning it a bit back and forth with your finger (obviously don't touch metal strip - can't shock you, but if it blows while your touching it, it'll sting).

If that's not it, then Wally's the next step.

Greg

 

Wally,

You're absolutely amazing! The fan does run on DEFROST but not on heat or A/C.

I re-read the owner manual on relays and fuse chart but I cannot see any relay labelled as "blower relay".

However, from the manual there is a relay, number XXI, that is fresh air fan, is this the one I need to replace?

There are also three relays, XVIII, XIX, and XX for extra cooling fan for A/C and retractable headlight relays, are these related to this issue?

I am going to login to 928 Specialists website to confirm these relays as well.

Greg,
Yes while I have the fuse panel opened, I am going to check the fuse as well. Do you happen to recall which fuse number? I gather it is #17, but it is only labelled as heating in the owner manual. Thanks!

 

Okay. After I sent the last message to Wally and Greg, I ran a search under "blower relay for A/C" and came across another great explanation from Wally.

He indicated the blower relay is XXI and defrost relay is XXII for my 84. From the reading, it appears fuse #17 should also be checked.

Wally then mentioned to jump terminals 30 & 87 of relay XXI to see if the fan would work in the non-defrost selection.

Guess what...I am heading out to the garage now and will report later if this resolves my problem! Thanks a lot guys!

 

Hi Tony,
To keep your weekend cool, I'm sure you can do without defrost for a couple of days. pull the defrost relay (XXII), and substitute it for A/C (XVIII) or blower, (XXI) - whichever is dead: I haven't tried that, but all three use the same relay - so should get things cool again.

 

Porsche930... Fuses 9(8 A.) & 17 (25A.)
and relay XXI (blower)are your best bets.

G'luck.

 

Hello to all,
I pulled the XXI relay and noticed terminals 30 & 87 with a little discoloration probably due to heat and age. Fuse #17 is okay. I jumped the terminals, started ignition, and got fan right away. I then used a very fine sandpaper to clean the relay prongs to shine. Reinsert XXI, and wow!! everything is back to normal now. Thanks a lot to everyone on this forum. This is absolutely the greatest place I want to be for my 928! Have a great weekend, and now I can use my A/C since the weather is going to climb to 90F later today till Monday. Enjoy indeed!

Garth, how are you doing lately?...definitely hardly use the defrost compare to the A/C, and I noticed these relays are interchangable too. Have a great weekend!

Macreel-I checked all the fuses and they all look fine. Thanks too!

Wally-Many thanks for your first instruction!