Weird Heater Blower Relay Burnt Issue
06-27-2011, 10:45 AM
#1
Burning Brakes
Thread Starter
Weird Heater Blower Relay Burnt Issue
Long time lurker, and first time poster, etc 
Two weeks ago joined the 911 family for the first time
My baby is a 93 C2 and she's gorgeous and wonderful to drive! You guys are lucky to have enjoyed these cars.
But I got a problem, which is a melted heater blower relay plug.
The back story is that when I got the car, the heater (it's winter now in Australia) could only rustle up a feeble stream of air through the dash vents. AND it was blowing the #1 fuse constantly.
I searched and searched the forum for answers, but the obvious ones (dying cabin blowers) weren't it. Eventually I realised the heater blower fan in the engine bay wasn't coming on, and traced that to the relay when the 30A fuse turned out to be ok. Basically the relay was loose and about to fall out. I pushed it in firmly, the heater blower kicked into action, and for about a week, life was good
But then today, the fan kept going after I shut down the engine. It's a cold evening, so I knew enough from reading forum posts that something was wrong.
After looking at some old posts, it seemed like a dead heater blower temp sensor might be the culprit.
But it tested just fine for continuity.
And this is when I discover that the blower relay is a little burnt-looking to say the least
Very burnt-looking actually at terminal 87. Now, I didn't remove the relay to inspect it when I discovered it was loose last week, so I don't know if it was already like this...or it became like this in the past week.
So much so, that it melted the cover of the relay a little and it popped off when I tried to wiggle the relay off.
I removed the a/c condensor relay, which is the same and plugged it in place of the heater blower relay, and it seemed to restore normal function.
But has anyone seen this burnt connector issue before? I'm thinking maybe it's a side-effect of the relay being loose, and a poor connection caused it to heat up?
Two weeks ago joined the 911 family for the first time
My baby is a 93 C2 and she's gorgeous and wonderful to drive! You guys are lucky to have enjoyed these cars.But I got a problem, which is a melted heater blower relay plug.
The back story is that when I got the car, the heater (it's winter now in Australia) could only rustle up a feeble stream of air through the dash vents. AND it was blowing the #1 fuse constantly.
I searched and searched the forum for answers, but the obvious ones (dying cabin blowers) weren't it. Eventually I realised the heater blower fan in the engine bay wasn't coming on, and traced that to the relay when the 30A fuse turned out to be ok. Basically the relay was loose and about to fall out. I pushed it in firmly, the heater blower kicked into action, and for about a week, life was good
But then today, the fan kept going after I shut down the engine. It's a cold evening, so I knew enough from reading forum posts that something was wrong.
After looking at some old posts, it seemed like a dead heater blower temp sensor might be the culprit.
But it tested just fine for continuity.
And this is when I discover that the blower relay is a little burnt-looking to say the least
Very burnt-looking actually at terminal 87. Now, I didn't remove the relay to inspect it when I discovered it was loose last week, so I don't know if it was already like this...or it became like this in the past week.
So much so, that it melted the cover of the relay a little and it popped off when I tried to wiggle the relay off.
I removed the a/c condensor relay, which is the same and plugged it in place of the heater blower relay, and it seemed to restore normal function.
But has anyone seen this burnt connector issue before? I'm thinking maybe it's a side-effect of the relay being loose, and a poor connection caused it to heat up?
06-30-2011, 12:24 PM
#4
Burning Brakes
Thread Starter
I ordered this little guy from my friendly neighbourhood Porsche dealer:
The thing is, there really isn't much room to work. This is after the heater downpipe is removed to free up some space in front of the fusebox.
Unbolt the relay holders from the fuseboard...
My theory is that when I bought the car, the relay was half hanging off and the heater fan was working only intermittently. The resultant poor connection caused a bit of arcing, which melted the plastic connector. I then discover the loose relay, push the relay back in position and it all works again. But all that melted plastic made it a high-resistance connection, and the 30A draw of the heater fan then melted it some more.
The heat then melted some of the internal insulation in the relay, and caused a short, which made the heater fan run all the time, even with the engine off.
To free up even more room (you'll notice that the length of wire going to the relays are very short) I even removed the back of the fusebox too.
My plan was to remove the existing terminals from the melted plug, replace the ones that were poor, but recycle the good ones. So this meant dremeling the old connector to get the terminals out.
You can see that the terminals have barbs, which mean that once they're popped in place, they don't wanna come out You can also see that they're quite delicate.
Once the old plug is all hacked apart, the terminals are free (and you can see only one of them is burnt, but pretty bad)
...the remains of the old plug
Pop on a new terminal to replace the burnt one (it's just a normal crimp spade connector, with solder melted into it)
Carefully slide the terminals back in place..
And button it back together again.
I put the heater on full blast, and went for a bit of a drive, and it seems to work fine again. The blower fan doesn't stay on after the engine is turned off (like before) and the fan comes on only when you dial up some heat.
Took the fusebox cover off and the relay and wiring aren't getting warm, and there isn't any weird smell, so fingers crossed this has fixed it for good.
The thing is, there really isn't much room to work. This is after the heater downpipe is removed to free up some space in front of the fusebox.
Unbolt the relay holders from the fuseboard...
My theory is that when I bought the car, the relay was half hanging off and the heater fan was working only intermittently. The resultant poor connection caused a bit of arcing, which melted the plastic connector. I then discover the loose relay, push the relay back in position and it all works again. But all that melted plastic made it a high-resistance connection, and the 30A draw of the heater fan then melted it some more.
The heat then melted some of the internal insulation in the relay, and caused a short, which made the heater fan run all the time, even with the engine off.
To free up even more room (you'll notice that the length of wire going to the relays are very short) I even removed the back of the fusebox too.
My plan was to remove the existing terminals from the melted plug, replace the ones that were poor, but recycle the good ones. So this meant dremeling the old connector to get the terminals out.
You can see that the terminals have barbs, which mean that once they're popped in place, they don't wanna come out
You can also see that they're quite delicate.Once the old plug is all hacked apart, the terminals are free (and you can see only one of them is burnt, but pretty bad)
...the remains of the old plug
Pop on a new terminal to replace the burnt one (it's just a normal crimp spade connector, with solder melted into it)
Carefully slide the terminals back in place..
And button it back together again.
I put the heater on full blast, and went for a bit of a drive, and it seems to work fine again. The blower fan doesn't stay on after the engine is turned off (like before) and the fan comes on only when you dial up some heat.
Took the fusebox cover off and the relay and wiring aren't getting warm, and there isn't any weird smell, so fingers crossed this has fixed it for good.
06-30-2011, 03:39 PM
#6
IHI KING!
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Great job! Can I suggest that you posted this in the 964 DIY section? See https://rennlist.com/forums/diy-submission-forum-135/
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06-30-2011, 07:46 PM
#9
Nordschleife Master
May I suggest that you check the part number on your ballast resistor that is plugged into the blower tube ducting. The original version has the number 964 616 550 01. The new version has an 02 on the end. The old version has been known to be responsible for engine bay fires:
https://rennlist.com/forums/964-foru...-the-hold.html
Just flagging this up for you to check in case the melting of the relay holder was in any way associated to the ballast resistor.
https://rennlist.com/forums/964-foru...-the-hold.html
Just flagging this up for you to check in case the melting of the relay holder was in any way associated to the ballast resistor.
06-30-2011, 08:37 PM
#10
Burning Brakes
Thread Starter
May I suggest that you check the part number on your ballast resistor that is plugged into the blower tube ducting. The original version has the number 964 616 550 01. The new version has an 02 on the end. The old version has been known to be responsible for engine bay fires:
https://rennlist.com/forums/964-foru...-the-hold.html
Just flagging this up for you to check in case the melting of the relay holder was in any way associated to the ballast resistor.
https://rennlist.com/forums/964-foru...-the-hold.html
Just flagging this up for you to check in case the melting of the relay holder was in any way associated to the ballast resistor.
Edit: just clicked on that link....HOLY CRAP....ok I won't be turning on the heater again until I check that out 100%
07-01-2011, 04:46 AM
#12
Nordschleife Master
You don't need to worry about turning on the heater because the ballast resistor is not associated with heating the cabin. It's role is to switch the blower into high speed mode when the temp in the engine bay is very high so that the excess heat gets dumped into the wheel arches. I guess (I'm no electrical expert) it must be linked to the relay in order for it to do that, hence why I suggested it would be worth checking it out.
07-30-2011, 09:34 AM
#13
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Join Date: Sep 2006
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Hi Babalouie!
Somehow I've missed your postings on Rennlist forums, but noticed them yesterday and then realised that we'd both bought our 1993 964 C2s via carsales.com.au at roughly the same time.
I'd seen your white C2 advertised on there along with my Wimbledon Green one. IIRC, yours was on for quite a premium, and thus out of my budget, so I never ended up enquiring after it. Mine was a little cheaper, but the PO was located in the Northern Rivers near Byron Bay, which made things somewhat difficult. Luckily, the PPI through the Porsche Centre Gold Coast showed only minor items to be addressed.
Considering that you prob paid a similar amount to what I did for the car (i.e. 993 money), I'd be interested in asking if you had considered the 993/996/Cayman as well, and what had made you decide on a 964?
Somehow I've missed your postings on Rennlist forums, but noticed them yesterday and then realised that we'd both bought our 1993 964 C2s via carsales.com.au at roughly the same time.
I'd seen your white C2 advertised on there along with my Wimbledon Green one. IIRC, yours was on for quite a premium, and thus out of my budget, so I never ended up enquiring after it. Mine was a little cheaper, but the PO was located in the Northern Rivers near Byron Bay, which made things somewhat difficult. Luckily, the PPI through the Porsche Centre Gold Coast showed only minor items to be addressed.
Considering that you prob paid a similar amount to what I did for the car (i.e. 993 money), I'd be interested in asking if you had considered the 993/996/Cayman as well, and what had made you decide on a 964?
07-30-2011, 10:40 AM
#14
Burning Brakes
Thread Starter
Hi mate!
Well, I was actually in the hunt for a 993, but they're so hard to find in Australia in a nice spec. Was looking for months, before a nice white 993 came onto the market, manual coupe in white on black, with low kms. Rang the seller and arranged to go and see the car 2 days later, but when I called back the next day, it was sold
Meanwhile, as you know, my car was originally advertised for, shall we say, a respectable premium (ie, more than 993 money). After letting that 993 get away, I decided to be more vigilant about cars coming onto the market And so one day I noticed that my car had been relisted with a somewhat lower price.
This time, I made sure I was the first to go and see the car, and together with some subterfuge and good luck, managed to ensure that I was the only person to see the car :P The seller was going out of town for business for a while, and the car was secreted away to a 911 specialist for a PPI, and so the car was taken out of circulation for the better part of a week
Anyway, my approach into 911 ownership was that I would be equally happy with either a 993 or 964. 993 has its benefits, but 964 has that classic 911 shape, the 911RS look is just so damn tough, plus it's a bit cheaper than a 993, so leaves more money leftover for mods
No regrets tho....the previous owners of the car really took fantastic care of it. Autohaus Hamiltons said thet it's the best 964 they've seen in years, but the PPI threw up the usual issues from lack of use. The car had been in a collection of 5 Porsches, so only saw under 1000kms of use per year. So you got the usual ballast resistor, engine mount, wishbone bush, and various other electical issues, but the good news was that it presented really well and the engine had great compression and leakdown figures. So it meant that I only had to do reasonably minor remedial stuff like this.
You going to the Porsche Club concours in October?
Well, I was actually in the hunt for a 993, but they're so hard to find in Australia in a nice spec. Was looking for months, before a nice white 993 came onto the market, manual coupe in white on black, with low kms. Rang the seller and arranged to go and see the car 2 days later, but when I called back the next day, it was sold
Meanwhile, as you know, my car was originally advertised for, shall we say, a respectable premium (ie, more than 993 money). After letting that 993 get away, I decided to be more vigilant about cars coming onto the market
And so one day I noticed that my car had been relisted with a somewhat lower price.This time, I made sure I was the first to go and see the car, and together with some subterfuge and good luck, managed to ensure that I was the only person to see the car :P The seller was going out of town for business for a while, and the car was secreted away to a 911 specialist for a PPI, and so the car was taken out of circulation for the better part of a week
Anyway, my approach into 911 ownership was that I would be equally happy with either a 993 or 964. 993 has its benefits, but 964 has that classic 911 shape, the 911RS look is just so damn tough, plus it's a bit cheaper than a 993, so leaves more money leftover for mods
No regrets tho....the previous owners of the car really took fantastic care of it. Autohaus Hamiltons said thet it's the best 964 they've seen in years, but the PPI threw up the usual issues from lack of use. The car had been in a collection of 5 Porsches, so only saw under 1000kms of use per year. So you got the usual ballast resistor, engine mount, wishbone bush, and various other electical issues, but the good news was that it presented really well and the engine had great compression and leakdown figures. So it meant that I only had to do reasonably minor remedial stuff like this.
You going to the Porsche Club concours in October?
07-31-2011, 02:18 AM
#15
Super Duper Moderator
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Welcome - nice DIY
I'd suggest replacing the fuse in that circuit too - just in case it is defective.
Shall I move this to the DIY forum for you with a title like "Replacing rear blower fuse plug" or something like that?
Marc
I'd suggest replacing the fuse in that circuit too - just in case it is defective.
Shall I move this to the DIY forum for you with a title like "Replacing rear blower fuse plug" or something like that?
Marc