[banditsc]

Need some thoughts here. The car normally runs cool, it was in the high 90's yesterday and it ran fine even in traffic the temp stayed fine. When I used my A/C that all started to change, while sitting in traffic the A/C wasn't causing any issues, but once I got moving with the A/C on it pushed very close to the red. I would have figured it would cool down with 70+mph winds moving thru it. This is against all my normality, you normally overheat sitting in traffic, not while moving at speed. My only thought was that maybe the compressor is causing the issue, I can hear a slight groan from it that almost sounds like the bearing is starting to tighten up. But there isn't much power loss when I have it on, and have no issues taking off from a stand still with on. The only thing that has changed related to the A/C since I last used it, is the belt for the A/C was changed. Perhaps the old belt allowed it to slip a little compensating for a tight compressor, but I heard not squealing before and the compressor noise maybe normal on this car.



Car has fresh coolant, thermostat, water pump somewhere in the last 10k miles, all fans operating normally, about 99.99% sure all air out of system. Only mods are air box and a unknown brand chip. Somewhere around 82k on the clock now.

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[968rz]

You may have checked this but are the fans running with the AC on? They should run non-stop as soon as the button is pushed (engine running of course), just a thought.

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[JWahlsten]

What is your voltage gauge doing while the A/C is running? If your voltage drops and the temp goes up you have a ground problem and need to clean the grounds. This happens a lot.



If not, I agree with the above. Check the fans.

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[banditsc]

The fans are in high speed mode with the A/C on. I will check the voltage, it's usally hangs out right around the 12 volt line. That reminds me, I really think I was crazy on this, but I could swear the car runs slighlty warmer when I run with the headlights on, jury is still out on that though. Lights are on a night so it should be running cooler in the night air, which is why I think it might be warmer with the lights on.



Does anyone have a guess on which ground point might cause this issue? Just a wild guess..



By the way, the contacts on the fan ballast resistors are either cleaned or replaced, that was one of the first things I found when I got the car. The fans didn't run quite right and the car was running warm, one of the pucks connectors were corroded and replacing them fixed the cooling issue.

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[banditsc]

What if I were low on oil in the A/C system, wouldn't that cause more heat in the bay and cause the compressor to work harder? Any thoughts how I could check that?

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[flash]

i tend to doubt that the ac unit itself is contributing to the cooling system running hot



i would first check the new components - the first thought of most people is that "it's now, so it should be fine" - the reality is that it is frequently "it's new and wasn't installed properly, or failed"



then, i would manually check the water temp to see if the guage is reading accurately - the temp sender is know to fail, and there could be some sort of problem electronically that shows up when you engage the ac - this could easily be a grounding thing- a circuit needs the same resistance on the ground side as the power side to have a guage read properly - if you have a bad ground, and then load it up with another circuit, it could affect the reading

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[banditsc]

I'm going thru and pulling and cleaning the grounds today. So far have done the battery itself and the ground point there, the main ground on the bell housing and a ground at the headlight near the compressor. Everything I have pulled off looks fine with no corrosion, but they all got sanded anyways.



The car also has the lower temp fan switch in it. I really don't think there are any water pump issues, I wasn't the one who replaced it, the previous owner did within the past 10k or so by a Porsche dealer, so it was most likely a new Porsche pump.



The way the gauge slowly climbs up to the red makes me think it reading correctly, but I could be wrong. I will continue to search for grounds and clean..

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[flash]

there is one behind the cluster that is known to get dirty - i don't know where it is exactly, but i think the diagram in the workshop manual shows it



there is another ground under the car on the front cross member too

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[banditsc]

[quote name='flash' post='36740' date='Jun 10 2007, 01:46 PM']there is one behind the cluster that is known to get dirty - i don't know where it is exactly, but i think the diagram in the workshop manual shows it



there is another ground under the car on the front cross member too[/quote]



I'll check those, I know the cross member has a good coating of oil from the power steering leak I haven't stopped yet <img src="/forum/images/smilies/968/mad.gif" class="smilie" alt="" /> . Did just notice I now have PS leak on the driver side now so it's looking more like the rack that was installed about 5k miles ago before I bought it. <img src="/forum/images/smilies/968/mad.gif" class="smilie" alt="" />



Back on topic, I noticed that the high speed fan doesn't kick on when the A/C is turned on, but only when the car gets hot enough to I guess warrant it. Is that the norm, I was under the impression it was always on when you press the condensor button. Perhaps one the relay's has gone south on me.

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[Mark]

Both fans should come on when you turn on the AC

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[968rz]

[quote name='Mark' post='36751' date='Jun 10 2007, 04:25 PM']Both fans should come on when you turn on the AC[/quote]

+1



Find the AC fan relay and (with the AC on) tap the relay and see if the fan starts (could be a bad relay)

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[JWahlsten]

[quote name='968rz' post='36756' date='Jun 10 2007, 08:48 PM']+1



Find the AC fan relay and (with the AC on) tap the relay and see if the fan starts (could be a bad relay)[/quote]





+2



Check the grounds behind the instrument cluster as well. Those are known to get corroded. One of the items I added to my last 944 turbo was the Ice Shark lighting kit. This is NLA as Dan Wray died a while back, but what he gave us was the knowledge that adding a supplemental ground by from the engine to the cross member helped settle a lot of ground issues down.



If you can find one of these kits available, the workmanship was exquisite, and the voltage levels in the car were MUCH better.

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[968rz]

[quote name='JWahlsten' post='36758' date='Jun 10 2007, 08:16 PM']but what he gave us was the knowledge that adding a supplemental ground by from the engine to the cross member helped settle a lot of ground issues down.



If you can find one of these kits available, the workmanship was exquisite, and the voltage levels in the car were MUCH better.[/quote]

Adding that ground is still an issue? I remember having to do that to my 79 924, one more thing on the list <img src="/forum/images/smilies/968/dry.gif" class="smilie" alt="" />

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[banditsc]

[quote name='JWahlsten' post='36758' date='Jun 10 2007, 09:16 PM']+2



Check the grounds behind the instrument cluster as well. Those are known to get corroded. One of the items I added to my last 944 turbo was the Ice Shark lighting kit. This is NLA as Dan Wray died a while back, but what he gave us was the knowledge that adding a supplemental ground by from the engine to the cross member helped settle a lot of ground issues down.



If you can find one of these kits available, the workmanship was exquisite, and the voltage levels in the car were MUCH better.[/quote]



I'll check on the relay. I wish Dan was still around for his kits, I put his ground kit in my pas 944S and the ground cable was beautiful. I wish I could get one of those for my car.

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[banditsc]

While I was under the car today looking over my latest PS leak (more on that later), I noticed a water drip. I saw a drip of water from the upper radiator hose and evidence of water coming down on the thermo switch. So I moved from under the car to the top and pulled the upper rad support and found the clamp to be tight, but the hose didn't appear to be on all the way, I loosened it up and pushed it back on a good ways and retightened it good. Judging by the water marks it appears to have been working it's way off. Perhaps with that small drip there some air has been allowed to come back in and and the system wasn't able to pressurize as much as it should. Though it was just a drip from there, it didn't appear to be any kind of pressurized leak. I will re-bleed the system and see how it does now.. Also the fans do come on when the condenser button is pushed, not high speed, but both fans are on.



The power steering was less then entertaining, I feel like a Dutch boy sticking his finger in a hole in the dam only to have another hole open. Been fighting the leaks for sometime, usually stopping them until a new one appears. This time the outer seal on the driver side of the rack is shot. Oil flowing from the alignment plug hole and air and oil coming out when I squeeze the boot. The rack was replaced about 5k miles ago and a little less then a year ago by a reputable Euro shop in Charlotte, but was done for the dealer I bought the car from not me and they are about 3.5 hours away so I'm not even going to bother with them, I'm sure I could get them to help, but it's not worth the 7 hours of driving time. A little history, years ago when I bought my previous P car a 944S it had a bad rack when I bought it (I knew that), put in a quart of oil start the car and a quart of oil instantly appears on the ground, so I replaced it along with a couple of bad hoses, it didn't feel right from the start but the distributor said to drive it, it needs to break in, well it didn't and another replacement rack later it was fine (bad rebuild). So I am less then enthused about working on the PS in the 968. I am really leaning towards throwing some Lucas Oil PS stop leak in to see if it does anything, bottle says 100% guarantee. I figure I have nothing to loose at this point since I'm looking at rebuilding this rack and most likely resealing the pump at the same time, so why not, maybe it will buy me some time..

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[flash]

if those radiator hoses are the original ones, replace them - they lose their elasticity after time, and will start to leak



bummer about the rack



i fear this is yet another in what will prove to be a long stream of leaks and rubber parts failures that will eventually get around to all of us - such is life with a 14 year old car though

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[ron1688]

How close was it to the red? If the temp is in the high 90s and you are running over 70MPH with your A/C on, I say it's normal for the temp gauge to be on the high side. 4 some years driving between Sac and Vegas during summer with the 968 says its fairly common for the temp gauge to rise pretty close to the red when you are driving somewhat hard with the A/C on. I am sure if you turn off the A/C, your temp will drop....

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[flash]

i have never seen it actually hit the red on my car, including the day it was over 100 in the shade at willow springs and i was passing out from the heat, though it got close for a second once when i fired it up and it was that hot - once i got moving (and we are talking less than a minute), it dropped back down to 9:30, and then down to just below 9



i do have about 8% more exposed cooling area than stock, am running water wetter as well as a 50/50 mix of coolant, and do have the lower temp fan switch, so that may account for why it runs that cool



my system is also tight - i check my reservoir cap to make sure it is holding proper pressure, and make sure i have no leaks - a properly pressurized system makes a HUGE difference in cooling



i'd start with making sure you can hold 13psi at temp

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[RPM]

If the temp is in the high 90s and you are running over 70MPH with your A/C on, I say it's normal for the temp gauge to be on the high side.

Actually my car runs relatively cool (below 9 o'clock) at speed, even in the heat and humidity, with the A/C on. It is when airflow is low in stop-and-go traffic that the gauge starts worrying me.

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[sp4149]

[quote name='flash' post='37106' date='Jun 15 2007, 05:52 PM']i

my system is also tight - i check my reservoir cap to make sure it is holding proper pressure, and make sure i have no leaks - a properly pressurized system makes a HUGE difference in cooling



i'd start with making sure you can hold 13psi at temp[/quote]



Flash, what is the pressure for the reservoir cap? It seems it was 13psi for the 944s but that 16psi is called for on the 968 parts searches I have been doing. I replaced the coolant tank last weekend, it was just too hard to tell the coolant level due to staining, prior to the head gasket failure. I need a new cap as well, I borrowed one from our 944. but it appears to be a lower pressure. The 968 Behr cap is stamped 150 while the 944 Behr cap is stamped 100.

-sp4149

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