overheats when I turn on airconditioner

944for-ever · 08-01-2006, 03:25 PM

My '84 944 usually runs at the center mark on the temp gauge. but this weekend when I turned on the a/c the needle would climb all the way over to the right side of the gauge, it would take about 5 miles to do so. once I turn the a/c off it stayd between the third and fourth mark all the way home, about 40 mies. granted it was 105 degrees in the shade. It had never ran that hot before, and it usually cooled quicker than that too. both cooling fans were working, and the thermostat is les than a year old, the a/c condensor is clean, The radiator seems to be clean but I got a new one on the way. the only thing left is the waterpump, or am I missing something. any input would be greatfully appreciated.

Eldorado · 08-01-2006, 04:01 PM

my uneducated opinion is saying that your car is running a little hot in the first place... half way up the gague is pretty steamy...

shikzachaser · shikzachaser's Garage

Make sure the second fan is coming on with the A/C.

Steve

mscromer · mscromer's Garage

Someone might be able to verify this but aren't the fans suppose to kick into high when the A/C is turned on? Might check that if this is true.

Razorback1980 · Razorback1980's Garage

You may also want to bleed the cooling system to make sure it has no air. Is the water pump leaking fluid? If not, then the water pump probably is not the problem. Also check your gauge to make sure it is working properly. Use a thermometer to make sure the gauge is accurate.

mih0001 · 08-02-2006, 10:58 AM

mscromer, you are right, on my 84, the fans automatically kick on when the a/c is switched on (even when the compressor does not kick on). but back to the origional problem, is the radiator cap new? if you do not have good pressure in the system that could be a part of the problem

shikzachaser · shikzachaser's Garage

Normally the one on the passenger side comes on w/ the A/C. If only the driver's side one is working it can also cause this problem, it happened to me. It's certainly easy to check.

Steve

944for-ever · 08-02-2006, 04:16 PM

well so far heres what I got: radiator is just over 2 years old, lower temp thermostat and lower temp thermoswitch are 1 year old, both cooling fans work the way they should, one of that fans is a 6 blade the other is a 3 blade. Im getting another 6 blade to replace the 3 blade, the water pump does not leak or sqeel. does anybody know how many degrees each mark on the temp gauge is, because I just bought one of thos guns for checking temperatures. So I'm going to put the car back together start it up and each time the needle gets to a mark on the temp guage I'm going to point the gun at the radiator hose coming off the motor and see what the temp is.

Eldorado · 08-02-2006, 04:19 PM

checking the temp of the hose might not give you an accurate reading.. rubber is, after all, an insulator...

944for-ever · 08-02-2006, 04:41 PM

yeah maybe I should check the elbow at the top of the motor that the radiator hose comes off of.

AaronM · 08-02-2006, 04:56 PM

Degrees in centigrade, from FR Wilk's site:

http://frwilk.com/early944/misc/watertemp.htm

944for-ever · 07:22 PM

I went to clarks garage and started to check my tempeture sending unit. He tells how to check the later style with 2 prongs, but not the early style with one prong. Does anybody know how, and what the hell is a potentiameter, cant I just use a volt/ ohm meter.

Ferrara_racing · 08:43 PM

Quote:

Originally posted by Eldorado
my uneducated opinion is saying that your car is running a little hot in the first place... half way up the gague is pretty steamy...

Mine used to run at the 12:00 position all the time and oscillated from 3/4 back to half on hot days, especially caught in traffic. The car was always properly cared for, and ran like a Swiss Watch to the day I sold it. I owned my 44 over a decade and IMHO the A/C technology of the time caused a noticeble reduction in power in a car that we all get used to having 100% of. The system is inherently weak, even in factory condition, it's not adequate and I believe contributed to overheating in a car whose cooling system shows the inexperience of a company venturing into water pumpers. The large rear hatch window is also a huge factor in the cabin greenhouse effect.

UconnTim97 · UconnTim97's Garage

My car runs tip top, and has almost 62K miles, and always runs at 1/2 (12:00) on the temp gauge. Though in this heat lately, it has struggled and runs at 3/4 in traffic with the AC on. It cools back to 1/2 once the car is moving again. You have to remember it is a 20+ year old car....

Paul Glasson · Paul Glasson's Garage

Had same problem-turned out to be the belt was a little loose connecting Aircon and water pump

Razorback1980 · Razorback1980's Garage

Paul, your post really confused me....my water pump doesn't run off my Aircon belt....which brings up an interesting point. When was the last time your belts were tensioned?

AaronM · 08-03-2006, 08:26 AM

Quote:

Originally posted by Razorback1980
Paul, your post really confused me....my water pump doesn't run off my Aircon belt....which brings up an interesting point. When was the last time your belts were tensioned?

None of the 944's drive the water pump off the A/C belt... They all drive it off the back side of the timing belt.

944for-ever · 08-04-2006, 12:53 PM

well I went out and bought one of those guns for checking temperatures, when I took my reedings I pointed the laser right on the threads of the sending. according to the diagram on clarks garage. the first tick on the temp gauge is supposed to be 68 degrees celcius, according to my heat check gun it says mine is 54 degrees celcius. the middle mark is supposed to be 89, mine is 64. the third mark is supposed to be 97, mine is 70. Is my temp sending unit screwed, or is it the gauge itself?, I'm thinking it's the sending unit.

gtroth · 05:41 PM

You might start to think of cleaning some grounds, particularly those on the engine. That lowered the reading ~ half a division on my gauge (note that mine's a late 944). Especially if the gauge jumps when you turn on big loads (headlights, rear defroster, AC...).

Does the needle jump when you turn on the AC or climb slowly?

edit - just reread your original post where it says that it climbs slowly. Still, does it jump at all?

Paul Glasson · Paul Glasson's Garage

Quote:

Originally posted by Razorback1980
Paul, your post really confused me....my water pump doesn't run off my Aircon belt....which brings up an interesting point. When was the last time your belts were tensioned?

Embarrasing-Should have said Alternator/Aircon belt, which for some odd reason is referred to as a fan belt, even though the fans are electrically driven.
When it was slipping about 1 year ago was last time I checked,as my aircon gave up the ghost . Have been trusting the mechanics that do most of my repairs,as you can tell I mostly tinker.
At that time the belt seemed pretty tight to me as it would take about a half turn. I was worried about tightening it more as I thought it would put too much strain on bearings of the alternator.