A/C Relay Question - front condenser fan inop

[wwest]

Kuehl...

There's more involved in a relay's operation than just allowing current to flow or not. Any type of inductive load, many are, turned continuously on and off over the years and the contacts will erode away. Sometimes you can have an average current, measured by a meter, well within the rated range for the relay (or fuse, think fuel pump) contacts, but with DC motor startup or pulse content 10 times higher.

[fred cook]

Originally Posted by howard freeman

Fuse 20 powers the relay for the aux fan. Try rolling or replacing that fuse,they will corrode,use only copper element fuses. No Aluminum !!!!! The relay for the aux fan is seperate from the system relay in the box. That one is on the relay panel. electrical diagram is here on this site.
Howard

This fuse powers both the front condenser fan and the evaporator fan. If you do not have the headlight washer option, move one of the fan wires (bottom of the fuse panel on fuse 20) to fuse 19. This will make your old fuse panel much happier!

Or, you could go all out and buy one of my ATO fuse panels!

[kuehl]

West,

I agree with you. Hammering a 15 amp rated relay with 19+ start up loads for milliseconds, seconds, or minutes, and continual seasons of 19 amp average loads will surely erode or fuse the contacts. Good point !

Griff

[Jim727]

Originally Posted by fred cook

This fuse powers both the front condenser fan and the evaporator fan. If you do not have the headlight washer option, move one of the fan wires (bottom of the fuse panel on fuse 20) to fuse 19. This will make your old fuse panel much happier!

I'll endorse that. After my a/c upgrade I kept blowing the fan fuse any time I got the blower over about half-speed. I really didn't want to increase the fuse size on old wiring so I split the front fan off on its own circuit. Problem solved.

Any chance you'll make ATO boxes for the earlier cars?

[fred cook]

Originally Posted by Jim727

I'll endorse that. After my a/c upgrade I kept blowing the fan fuse any time I got the blower over about half-speed. I really didn't want to increase the fuse size on old wiring so I split the front fan off on its own circuit. Problem solved.

Any chance you'll make ATO boxes for the earlier cars?

Working on it. I need to get an up close and personal look at the earlier fuse panel mounting brackets to get some measurements, etc. Eventually I hope to be able to cover all years from 1965 thru 1989.

[kuehl]

Originally Posted by fred cook

Working on it. I need to get an up close and personal look at the earlier fuse panel mounting brackets to get some measurements, etc. Eventually I hope to be able to cover all years from 1965 thru 1989.

[mthomas58]

Originally Posted by mthomas58

The fuses all look OK but I do have some Alum that I will replace with copper. I need to check the wiring to the fan relay socket.....had battery replaced recently and something could have been pulled loose.

I have not opened up the smugglers' box yet to check the relay (I've ordered a new one already as I did not replace it when I did my A/C system 2 years ago. On drive back from a trip this AM I had the A/C on to test function and I started to get a hot electrical smell so I shut it off. All of the wiring, fuses and relays outside the smugglers box look OK so I am anxious to see what going on in there.

Finally had some time today to work on the A/C. Opened up the smuggler's box to replace the A/C relay and found the source of the burning electrical smell. Terminal #30 on the A/C relay socket has melted. Swapped out the relay and the front condenser fan is still inop so more troubleshooting is needed. I do plan on moving the power source for the front condenser fan from fuse #20 to #19. Additionally, I found that one of the fans on the dual rear fender condensers is inop. More work to do in several areas.

[kuehl]

Mr. Thomas

Your relay appears to be original?

What is the amp rating stamped on it?

[mthomas58]

It does appear to be original as it is stamped 10/ 86. Amp rating is 30A.

[kuehl]

Originally Posted by mthomas58

It does appear to be original as it is stamped 10/ 86. Amp rating is 30A.

Thanks Mark.

I assumed 30 amp was stock out of the factory.
So, did you order a 15 amp or 30 amp?

[mthomas58]

I ordered the factory replacement from the Dealership - 15A which is installed.

Now trying to figure out how to move the front condenser fan power source from fuse #20 to fuse #19. Not readily apparent from looking at the fuse panel - .....and I just figured out that I was looking for wires per a 82 Wiring Diagram. Need to locate the correct one for a 1987. Looks like I will need to pull the panel and look behind it to see where the power for the front condenser fan ties into fuse #20 (center blue fuse on three fuse block - far left side of photo)

[mthomas58]

While down, I've decided to go ahead and replace the Temp Switch which I think is also original.

[kuehl]

The factory relay was a 30 amp.
The 'factory' replacement is a 15 amp.
However the load is equal to or greater than 15 amps.
Think about it.

[mthomas58]

OK, 30A relay ordered. Here are a couple of great pics from a fellow Pelican on how to move the front condenser from fuse #20 to #19 to reduce the load and heating on fuse #20 as suggested and done by several folks here.






Remaining project to do's:

(1) Replace 15A new factory replacement relay with 30A relay in accordance with orig relay spec.

(2) Replace Temp Control Switch

(3) Relocate front condenser relay power source to fuse #19 (a/k/a #3) per pics above. A/C fuse is #2 on the small 3 fuse block from back to front and #19=#3. Multiple references found - Bentleys lists the fuses in three blocks and the cardboard fusebox lists the fuses from front of the car back.

(4) Finish troubleshooting front condenser inop situation. Fan works fine if hardwired to battery. Check condition of panel relay and relay socket wiring.

(5) Troubleshoot front rear fender condenser (fan inop). Rear fender rear condenser fan on same circuit is working fine.

(6) Recharge upon completion of 1-5

[mthomas58]

Update: Headed over to Augusta today for the Masters. Possibility of picking up my boss at the airport in Columbia so I thought I would try to get the A/C working or would have to rent a car.

Confirmed rear fender spal fan on front condenser dead. Happened to have a spare from my deck lid 3 fan project that I did not use and is identical to the dead fan. Replaced and problem solved.

Tried jumping front condenser fan relay socket - nada. Finally figured out that the relay socket is mounted in the fuse panel with pin 30 at the 3 o'clock position. All other relay sockets have pin 30 at 6 o'clock. I did not think that the relay could be inserted at any position other than correct. WRONG - I had pins 85 and 86 where 30 and 87 should have been so the fan has been inop for I don't know how long. What a dumb ass!

So, except for installing the 30A relay (vs the new 15A A/C relay) and replacing the temp switch (both arrive tomorrow) and moving the front fan to fuse #19 all components are operational so I though I would charge the system and give it a try. Pulled vacuum and charged system for the trip and the A/C ran great all the way!

Life is good again!

[db_cooper]

Pretty cool here in Georgia this morning..you may not need the A/C after all. A report on the Masters is required.

[86 911 Targa]

Originally Posted by mthomas58

Update: Headed over to Augusta today for the Masters. Possibility of picking up my boss at the airport in Columbia so I thought I would try to get the A/C working or would have to rent a car.

Confirmed rear fender spal fan on front condenser dead. Happened to have a spare from my deck lid 3 fan project that I did not use and is identical to the dead fan. Replaced and problem solved.

Tried jumping front condenser fan relay socket - nada. Finally figured out that the relay socket is mounted in the fuse panel with pin 30 at the 3 o'clock position. All other relay sockets have pin 30 at 6 o'clock. I did not think that the relay could be inserted at any position other than correct. WRONG - I had pins 85 and 86 where 30 and 87 should have been so the fan has been inop for I don't know how long. What a dumb ass!

So, except for installing the 30A relay (vs the new 15A A/C relay) and replacing the temp switch (both arrive tomorrow) and moving the front fan to fuse #19 all components are operational so I though I would charge the system and give it a try. Pulled vacuum and charged system for the trip and the A/C ran great all the way!

Life is good again!

Yup, it is possible to install the round fuse panel relays out of circular alignment.

Your evaporator relay appears to have died a very slow death due to contact arcing/pitting,
thereby creating a series resistance leading to contact overheating.

Our '86 came equipped with a 15A relay, which I replaced with a fused 15A relay.

Also, please have a second look at the pics I sent.
T
Also, the front condenser blower fuse has been relocated from fuse #2 to #3.

Here are some A/C current draw values I recorded a while back:


Evaporator Blower Motor Current-Low Speed.


Evaporator Blower Motor Current-Medium Speed.


Evaporator Blower Motor Current-High Speed.


Front Condenser Blower Motor Current.