Sounds like my rig....

 

I thought I would check in. I installed a 150 amp RR Alternator I got for a steal from a pick and pull in TN. That did not change the voltage readings, which lead me to believe that I need to charge my battery, or it is possibly going bad. It's NAPA so when I have a minute I will stop in and have them test it.

However, in traffic, fairly thick at 91 degrees it held 202-204. This weekend we drove to Green Bay to visit some friends, and in some heavy traffic, got to 206, again 91 degrees, but it came right back down.

So, as obviously not an Electrical engineer, I am positing that the voltage readings are more related to my battery than the Alternator. Could the new alternator be running the fans more effectively by providing more amperage? I don't know. Was the lower amperage possibly creating a load on the engine? I don't know.

Most likely the temps are indicative of the conditions at the time. But could going from 91 to 98 degrees cause the system to run 20 degrees warmer? I don't know enough about thermal dynamics to say. Maybe there is a tipping point somewhere where the design is just inadequate to keep up.

At any rate, I regret not doing the inline mod, even though 99% of the time the 180 genuine does a really good job.

 

Well I wanted to test something over the weekend. I had a trip into Houston planned, and I had a rough week so I felt like some wind in my hair & listening to a V8 roaring down the road so I drove with the sunroofs open, front windows open, and no HVAC at all. My temps at 65-80MPH was 188-193F and even 184F when I slowed down. So all that 200-211F I’ve seen = just the heatsoak from the HVAC condenser! 180F OEM style thermostat is working flawless, it’s just so darn hot out the HVAC add’s that much temp to the engine.

I’m going to look around for a higher CFM efan for the condenser as I think that would help out. Just a little experiment & it proved to me that the OEM style cooling system is fine. Just the added heat from the AC condenser during the summer = higher temps.

How did you test the new 150AMP alternators output? Metering the battery with the engine off will tell you the condition of the battery. Engine off is usually 12.5-13.0v. With the engine on it should be 13.4 to 14.4v range. If it’s not that high clean all the terminals really good, make sure they’re good & tight, and make sure the alternator connection is also clean & tight.

 

Thanks Best! That is what I suspect, too.

I just plugged the 150 amp right in, no special set up. I have wire brushed the terminals really well. They do seem to develop a copper coler really quickly, not sure if normal. I used Vaseline on the posts per RAVE. All the grounds looked good and the connector to he alternator is a bit tough to tighten/loosen, but the threads are clean and should be making good contact. It seemed to turn over better, but that could be wishful thinking. I have not tested the ampereage, and that would have been a really good idea! I just am going off of the voltage reading on scangauge.

FYI, I have a 14" Flex a lite on mine after my original AUX Fan was too far gone to rebuild, to get it out I had to destroy the fan. It is on there with the plastic bolts/washers and mounted on the condenser. I don't love that, and have an original fan I picked to swap in when I get a chance. I had ordered a 16, but it would not fit.

I believe the P38 has two 12 inch fans for Aux, you'd know better than I, but to fit it you would need to relocate the dryer which I was not prepared to do. Maybe they are 10" fans, but I believe I saw that setup somewhere.

 

Gotcha! Yeah I’m gonna look around at the junk yard when I can. Usually mercedes & BMW’s use pretty high speed efans as aux fans.

 

The fan I picked has a Denso fan on it, if that is the stock fan, but I know you can source a new fan motor and replace the stock, whether it is higher CFM I do not know.

 

Yeah I’m gonna try to find the highest CFM 14inch I can get my hands on & test it out.

 

Well I’ve been unable to get any work done lately due to some house lists to catch up on but in the next week or two should have some more time. I know you’ve been hunting down a electrical problem as a possibility but my electric is in order and my condensor and cooling system check out so I suspect my a/c compressor. I get no squealing from the compressor and it engages and disengages normally and produces cold air inside the vehicle but I’ve noticed when the air is on at idle that the compressor gets so hot you can’t put your hand near it. I’ve hit the outside of the compressor with a i.r. temp gun and it is 220 degrees plus. My question is can a compressor create that much external heat while still creating cold air? Is it slowly destroying itself? I think this is my overheat at idle when a/c is running. With the outside temps you guys have bern seeing could you please maybe take a temp of your a/c compressor running at idle? Thanks

 

I'll put my temp gun in the car today and get you a temp off of mine.

The Heat of the compressor shouldn't make much difference, but I suppose it could.

Maybe you have a blockage in the A/C system that is causing the condenser to dissipate more heat than normal?

I don't believe my problem was electrical, just traffic and high temps overloaded the system with A/C, remedy would be inline thermostat which allows for much better coolant flow making full use of the radiator.

 

I’m with you on the inline mod. I’ll probably go that route when I get the compressor issue situated. Thanks in advance for the compressor temps