A/C Inoperative.. HELP PLEASE!!

[Jayboundless]

FYI...The photo is upside down for some reason.


Hello All, I've just bought my first 911 (85 Carrera) after 20 years too long. I purchased in Denver and drove it back to Omaha last week. During the drive, I had the A/C on although it wasn't blowing cold, (which the PO mentioned it wouldn't) After about 15 min, the blower stopped. When I turn the fan to any setting it doesn't work. The clutch doesn't' engage nor does the fan blow. I replaced the relay in the smuggler box as mentioned many times in this forum, however, still nothing. Also, there is no power at the evaporator blower at any fan setting. The bullet fuse in the #2 position (I believe, I'm not looking at it right now) checks fine at 12v at both ends. However I did just notice that there is a round relay (red in color) in the fuse box panel as well labeled Air Conditioning. That I have not replaced. Is this the culprit and is it the right part? In parts listed on Pelican and other Porsche parts retailers the red round relays always seemed to be referenced as Fuel pump relays.

Also, wondering if related due to the fuse at the #2 position, my seat adjustment switches on both sides quick working altogether, although they were very intermittent at all. But it is hot at that fuse and they are suppossedly intertwined at that fuse location.

Even though I'm not all that concerned about the a/c working due to there poor reputation, I just mentally can't stand something not working when it is supposed to.

My general questions are:
What does the bullet fuse control?
What does the relay I replace in the smuggler box control?
What does the red round relay on the fuse panel control and is it the right one?
I'm assuming it is the various blowers (evaporator, condenser and clutch)

I'm stumped....HELP PLEASE!!!

[Bob Kontak]

Originally Posted by Jayboundless

I just mentally can't stand something not working when it is supposed to.

You bought the wrong car, Bro. Go to the Dr and ask for the largest horse pills labeled "Chill out" and take a couple a day until the pain subsides. However, this is the mentality needed for keeping a 911 in good working condition.

Welcome to the forum, BTW.

Since you are a Porsche noob - we all were - get yourself the Bentley manual and a multi-meter and get to work. This is a chump-ass tiny problem so will be good to cut your teeth on.

[kuehl]

1) Looking at your picture, 2nd fuse from the right, is your primary AC fuse. It should be a blue colored 25 amp. Change it. This fuse provides power to the primary AC relay in the smugglers box and the front condenser blower motor relay on the power panel.

2) Relay in smugglers box is the primary AC relay:
It receives its power from the #2 fuse via a red/white wire to its terminal #30. When the ignition key is on power then goes out the relay’s terminal #87 via red wire to the evaporator blower fan speed switch.

3) If the evaporator blower fan speed switch does not have power to it via the red wire from the relay then issue is usually the relay, provided the fuse is good. If you turn on the
fan speed switch and you don’t have power to either of the 3 fan speed switch wires (red/green, red/black, red/white) then issue is the switch. You should also have power going out the green/white wire which leads to the thermostat. So if the evaporator blower motor switch is not sending power to the evaporator blower motor, it won’t run, and ditto on the compressor clutch.

4) When the fan speed switch provides power to the thermostat, if the thermostat is in a ‘make’ state’, meaning it is demanding AC (such as when your turn the thermostat to max cold, fully CW), then power travels through the thermostat out the solid green wire to front condenser ac relay (its terminal 86). At the same time power goes to the front condenser relay, since there is “Y” circuit or parallel circuit, power goes to the compressor clutch.
So, what the thermostat does is turns on the front condenser blower motor (via terminal 86 on the condenser blower motor relay) and the compressor clutch at the same time.

You can find the an earlier AC circuit here (basically the same as your year)
http://www.pelicanparts.com/911/911_Parts/Electrical/911_electrical_82SC_AC.jpg

The circuits you want to look at in the Porsche Shop Manual are under section 970-45 for AC and 970-43 for the seats.

If you keep popping the #2 ,25 amp blue fuse, unplug both the seats (underneath) and repair the switch that is fouling on you. They share the same fuse.

So, if you have power coming out your primary AC relay terminal 87, however no power coming out the evaporator blower motor switch as noted above, then most likely the issue is the blower motor switch.

While you are at it, test the evaporator blower motor alone using a direct DC connection off the battery, if it does not turn, replace it.

Also check to see if anyone put an inline 7.5 amp fuse between the front condenser blower motor and terminal 87 for the ac blower motor relay mentioned. If you don’t have a fuse spliced in then do so right away.

And, when you get it fixed... then read: THE MR. ICE PROJECT

[kuehl]

Now, Now Bob. We are suppose to help the noobies.

[Bob Kontak]

Noobs get the love, too. Tough love, but love nonetheless.

[timmy2]

Tough Love ...
Spark shower! Bye Bye A/C

[Joeaksa]

Jeez Bob, chill out yourself a bit... Thats his FIRST post!

[DRACO A5OG]

Jay,

Welcome aboard, brother 85.

#2 fuse holder when it gets extremely hot will shrink the fuse and give you that intermittent power to the seats, windows and the AC. Using 2 or 3 of the components at one time will definitely shrink the fuse or pop it.

+1 you may have a short in the seats some where, most likely it is shorting on a metal suface under the seat or bad connect or both. If after that it still pops then it may be that fuse panel cluster which has too much resistance and needs to be swapped out.

If you do swap it out change the rails as well.

I went a step further and relocated the seat's power to fuse 1 so AC has only one dedicated fuse. Beware, you do this at your own risk.

Jim

[86 911 Targa]

Originally Posted by Jayboundless

FYI...The photo is upside down for some reason.


Hello All, I've just bought my first 911 (85 Carrera) after 20 years too long. I purchased in Denver and drove it back to Omaha last week. During the drive, I had the A/C on although it wasn't blowing cold, (which the PO mentioned it wouldn't) After about 15 min, the blower stopped. When I turn the fan to any setting it doesn't work. The clutch doesn't' engage nor does the fan blow. I replaced the relay in the smuggler box as mentioned many times in this forum, however, still nothing. Also, there is no power at the evaporator blower at any fan setting. The bullet fuse in the #2 position (I believe, I'm not looking at it right now) checks fine at 12v at both ends. However I did just notice that there is a round relay (red in color) in the fuse box panel as well labeled Air Conditioning. That I have not replaced. Is this the culprit and is it the right part? In parts listed on Pelican and other Porsche parts retailers the red round relays always seemed to be referenced as Fuel pump relays.

Also, wondering if related due to the fuse at the #2 position, my seat adjustment switches on both sides quick working altogether, although they were very intermittent at all. But it is hot at that fuse and they are suppossedly intertwined at that fuse location.

Even though I'm not all that concerned about the a/c working due to there poor reputation, I just mentally can't stand something not working when it is supposed to.

My general questions are:
What does the bullet fuse control?
What does the relay I replace in the smuggler box control?
What does the red round relay on the fuse panel control and is it the right one?
I'm assuming it is the various blowers (evaporator, condenser and clutch)

I'm stumped....HELP PLEASE!!!

Have a look at my post #2179 from yesterday.......pm me as needed.....

[86 911 Targa]

[Jayboundless]

For a brief moment I wondered WTH...really? I'm on a technical forum asking for some help in understanding an electrical issue and get berated for that??!!!

But "kuehl" and others came to the rescue and I'll have an easier go at figuring this issue out.

Also, after further digging, I just noticed (see photo) that there are no wires hooked up to fuse #2. So, it must be wired elsewhere (that will be fun).

I own the Bentley Service manual, but it isn't very descriptive in explaining the system nearly as well as "kuehl" did. Thank you very much!

One final question as I don't have the parts manual. Is the red relay the correct one for the a/c? The number on it is.. 21164-12 and 911.615.108.01

Thanks again for all the help!

BTW...Feel free to continue to publicly shame Bob for his lack of judgment.

[DRACO A5OG]

Hey Jay,

No worries, #2 holder does not have a wire but a connector "rail" from #3 holder (power in, the bottom of the holder is where it goes to the compononents).

As far as the red or black relay, the red ones is the correct relay. In a pinch you can use a black one but it may intefere with your radio receiver. With red you can't go wrong just a bit more expensive. What ever you do, do not buy the URO brand they are crapola.

Oh yeah as Kuehl stated place a proper "blue" fuse at #2. If you can, find ceramic fuses, the flaps plastic ones will just melt and shrink and cause a short.

J

[tazzieman]

Originally Posted by Jayboundless

BTW...Feel free to continue to publicly shame Bob for his lack of judgment.

Welcome!
Tone goes both ways! Many of us here like to get our cars just right and sometimes , if a component doesn't work , we just remove it and move on - even more rapidly .
If you'd said "this is really bugging me" or similar , Bob would've just kept quietly chugging away at his Bud.

[Kidasters]

Hey Jay. Welcome. We all have to start somewhere.

Listen to Kuehl. He sells some great A/C components - I'm running his rheostat fan switch, his front condenser and the super duper fan motor that he sells. All fantastic.

keep posting so that we can all celebrate your victory.

Ken

[aerodyn930]

Hello Jay, Welcome to the forum, I would recommend checking the current limiter that appears to be controlling the current in your A/C circuit, It is the square device above fuse number 2, These are designed to open the circuit once the rated current is reached , ( like a fuse but these are designed to re-set after a brief cool down period), Check for voltage in and out of this device as a starting point, This BTW is not stock , It is a way around a resistive fuse holder,

Hope this helps, Lou

[DRACO A5OG]

+1 not OEM, I do not have that device either.

[pavegeno]

As Kevin Costner said, "Dry land is not a myth!" Likewise, a functioning a/c in a 911 can be very comfortable even in triple digit temps. Once you figure out the baseline of your system's capability, talk to Keuhl. No BS and awesome products that just plain work. You won't regret it.

[mreid]

Should I post another picture of my burned up front condenser fan?

Follow Keuhl's advice!

[E Sully]

Jayboundless,
If you are on the forum much, or do some searching, you will find that Bob Kontak tries to be very helpful. His Tough Love must have come off a bit harsher than he meant.

[Flat Six]

Originally Posted by Jayboundless

One final question as I don't have the parts manual. Is the red relay the correct one for the a/c? The number on it is.. 21164-12 and 911.615.108.01

You can get a *.pdf copy of the factory parts manual here:

Porsche Classic Genuine Parts Catalogue - Classic Genuine Parts & Literature - Porsche Classic - Dr. Ing. h.c. F. Porsche AG

Originally Posted by Jayboundless

BTW...Feel free to continue to publicly shame Bob for his lack of judgment.

Easy . . . tone goes both ways. Bob's offered a wealth of technical wisdom and provided some stability to my temperment on more than one occasion. I, for one, trust his judgment and bristle at the thought of publicly shaming him for it.