AC Compressor Temperature

[WYDBODY1986]

Saturday when I was trying to chase down the reason for the fuse on the AC relay in the smugglers box burning I was using my IR thermometer to check the temperature on the wires and fuses. I happened to shoot the AC compressor while it was running and the temp was around 150 degrees on the body of the compressor while the surrounding surfaces were in 110 range. That struck me as high but is it really? does anybody know what temperature a Sanden 507 style compressor should run at? Ambient temp was about 95 and the car windows were open.

[88911coupe]

i just got a inferred therm as well and did the same thing, also got about the same reading and I recall seeing somewhere else that thats about the expected temp. seems a little high to me. Mine is a 508 so very similar

[86 911 Targa]

Originally Posted by WYDBODY1986

Saturday when I was trying to chase down the reason for the fuse on the AC relay in the smugglers box burning I was using my IR thermometer to check the temperature on the wires and fuses. I happened to shoot the AC compressor while it was running and the temp was around 150 degrees on the body of the compressor while the surrounding surfaces were in 110 range. That struck me as high but is it really? does anybody know what temperature a Sanden 507 style compressor should run at? Ambient temp was about 95 and the car windows were open.

Have a look at fuse #2 on the fuse panel.

I posted a fix a while back.

Gerry

[kuehl]

Originally Posted by WYDBODY1986

Saturday when I was trying to chase down the reason for the fuse on the AC relay in the smugglers box burning

Start at the feed fuse #2 on the primary fuse panel. Insure the wires are not corroded.
Check the fuse contacts for corrosion. Use a ceramic (not plastic) 25 amp fuse.
Next, check the spade terminals for the primary ac relay you have, clean any corrosion, cut back burnt wires. A 20+ amp relay is preferred.
Next, check how many amps your evap motor is drawing (an inexpensive analog 0-25 amp meter in line works fine) wired directly to the battery for full fan speed and then through fan speed switch's 3rd speed.

Originally Posted by WYDBODY1986

I was using my IR thermometer to shoot the AC compressor while it was running and the temp was around 150 degrees on the body, a Sanden 507 style compressor, Ambient temp was about 95 and the car windows were open.

Well you are putting a heavy load on the evap coil running windows open, but 150F (give or take because of IR emissivity) is fine (safe at 95F ambient).

[Discseven]

I've seen comp temps near discharge port at 160. Guessing ambient was 90'ish.

[kuehl]

If you think about it, R134a at a discharge pressure of 265 psi is 150F, while in at a suction pressure of 30 psi 35F.

And, when you look out the windshield and you see rain drops hitting it then you know its raining, or maybe a United Air dumped its grey water tank to save some fuel.

[WYDBODY1986]

Thanks for the responses, the fuses and the wiring all look very good and the wiring going to the evap fan was not getting hot so I replaced the crappy relay with the built in 15 amp fuse with a new bosch relay and the high temps I was seeing in the wiring to the relay and at the two fuses dropped from 140 degrees down to 100 so I think I found the culprit.
When I started checking temps of different things on the car while I was waiting to see if the new relay cured my problem I was a little surprised at how hot the compressor ran which I now know is normal

[kuehl]

Its more fun to look at the exhaust header temps.

[GH85Carrera]

If you get the AC tuned up and working at peak capacity the incoming refrigerant can help cool the compressor. This was on a 90 degree day after a 30 minute drive.

[kuehl]

Random Pics

Drier temp 118.6F operating




Evaporator outlet pipe 30F operating




Kuehl Center Vent 32F

[WYDBODY1986]

GH85, apparently I have some work to do because mine is definitely not that cold on the inlet side!

Kuehl, very Kuehl pics! makes it much easier to understand the refrigerant flow through the system

[WYDBODY1986]

I suspected I had a leak in the system because my vent temps have been creeping up all summer long, guess it's time to break out the gauges for a quick look see!

[Discseven]

^^^ Wydbod... Might want to take a look at underside of evap. (Look through passenger side intake. Put small camera in to pic it... or mirror.) Debris combined with condensate algae growth here in FL is temp killer.)

[gsxrken]

Originally Posted by kuehl

Use a ceramic (not plastic) 25 amp fuse.
Next, check the spade terminals for the primary ac relay you have, clean any corrosion, cut back burnt wires. A 20+ amp relay is preferred.

CG do you have a part number for the above 20A AC relay?
Looks like our host has the Porsche one but it's a 15A plastic fused one.



A/C Relay 91161510301 - Genuine Porsche - 911-615-103-01 | Pelican Parts


Other related question- does this relay power everything electrical downstream in the AC system? I ask because I have an intermittent scenario where my condensor fans and evap fan are blowing, but my compressor clutch is not getting power and I obviously do not have cold air. Very intermittant... wondering if that's possibly related to this relay or, if "fans running" means the relay is exonerated and my intermittant connection is elsewhere.

[kuehl]

You simply need a standard 5 pin, spdt, 12vdc, relay, commonly used for AC and things like aftermarket fog lights, etc.

It is more common to find 25,30 or 40 amp, either will work just fine

The pin outs are as below



maybe Pelican has one under a different PN

[WYDBODY1986]

Thanks Karl I did that when I checked the ac temp switch probe to make sure it was properly set all looked clean

[Rawknees'Turbo]

Originally Posted by WYDBODY1986

Thanks Karl I did that when I checked the ac temp switch probe to make sure it was properly set all looked clean

Karlicious is talking about the bottom side of the evaporator (visible through the intake duct which is behind the passenger floorboard) - not sure if you were aware of that. Karl's was so covered in mold/funk buildup on that side, that it looked like a flattened squirrel carcass was stuck to it!

[WYDBODY1986]

Yes thanks I was checking the bottom of the evaporator to make sure the temp probe was not sticking out the bottom of it