88 T/C Overheating only with A/C

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88 T/C Overheating only with A/C

Reply #30 – June 02, 2013, 09:23:07 PM

Normally the high side pressure should be 40* above outside ambient temp. So at 90* his high side should be 130* or 200 PSIG!!

OK How did you reduce the pressures on the system. Did you REDUCE THE CHARGE. Another words did you remove freon from the system to reduce your pressures???

Proper reading at 90* with RPM at 1400-1600

Discharge temps high fan AC set to inside air or MAX OPERATION!!

NOTE just look at the gauge it has the temp pressure tables right on the FACE for the freon you are dealing with!!!!

This system is charged properly and working efficiently. Bottom line it is all in the charts. Pressure and temp this is not brain surgery.

Once again i am leaning to a cooling system on a marginal basis. His cooling system is marginal at best. He needs more cooling.

88 T/C Overheating only with A/C

Reply #31 – June 02, 2013, 09:50:41 PM

No, at 2lbs 8, my pressures are just about what you're showing. But that's what I'm saying, by the chart, he's not out of spec, but it is higher than what I'm used to seeing.

88 T/C Overheating only with A/C

Reply #32 – June 02, 2013, 09:55:45 PM

Quote from: TOM Renzo;416506

Whenever converting tou must use less R134 as it is more efficient than R12 and that is a fact.

Care to explain this in more detail?

88 T/C Overheating only with A/C

Reply #33 – June 02, 2013, 09:59:58 PM

FOE nice chart but what is the FREON IT REPRESENTS. That cant be 12 or 134 in a car system. The only charts that i have seen this high is posted by HONDA. And they normally dont run that high. Pressures are to HIGH. Years back i came up with a wiring mod for the JEEP CHEROKEE. They delayed the AC condenser fan way to high. They turned the fan on @ 360-400 PSIG. This made the belt squeal on start up and running on some cars. It also burned out water pumps as mechanics were tightening the belts way to much to compensate for it. I made a change in the fan system to eliminate this issue and every dealer and owner in a hundred mile radious came to me to repair it. Made a tun of cash on that one.

Question when checking ac systems do you see the high side over 250* @ 100* outside??? Only if the evaporator is restricted or the system fan is not running or whatever. Over 220 PSIG is really pushing it. Just me and the TEMP CHARTS!!! What do you find with normal pressures on the cars you service at the dealer you work at. Just curious foe thanks

88 T/C Overheating only with A/C

Reply #34 – June 02, 2013, 10:02:33 PM

Quote from: JeremyB;416516

Care to explain this in more detail?

R134A is more efficient so you use less freon!!! When charging a converted system you charge DOWN. 10-12% BUT It runs at slightly higher pressures than R12.

88 T/C Overheating only with A/C

Reply #35 – June 02, 2013, 11:28:58 PM

Ok, I would say my chart was 134a. But lets be sure. Here I've got the R12 chart right out of our very own 88 Thunderbird Workshop manual.

And these are R134a tables taken from the Workshop manual for 98 Taurus.

They sure look like the same chart. I'd have to put hands on an original R12 vehicle WSM, as I suspect AllData may have swapped out the Charts for R134a. The Taurus charts came directly from FMCDealer.com Although it's worth noting that the test notes in the R12 chart specify blower to max, where in the manual, R134a charts specify blower to minumum.

88 T/C Overheating only with A/C

Reply #36 – June 03, 2013, 06:10:00 AM

What should the high side pressure be?

Like i said 40* past ambient is about the norm. More than that is something i would not like. Just me.

ROBIN AIR TECH SPECKS FROM THEIR ENGINEERING DEPT

With R12 systems, high side pressure is usually 1.8 to 2.1 times ambient temperature. That means on an 80 degree day, with moderate humidity, we would expect to see between 144 to 168 PSI on the high side. On hot humid days (with R12), you could say ambient temperature plus 100 PSI., and be pretty close.

With R134a it's common to see high side pressure between 2.2 and 2.5 times ambient temperature. On that same 80 degree day we would see between 176 and 200 PSI on the high side of an R134a system. The system operates in a specific range based on outside ambient temperature. Normally around 200 PSIG But not set in stone.

The owner of the car reduced the charge dramatically and lost high side pressures and in turn lost heat. He now does not overheat according to his post at highway speeds. So charging an AC system and knowing how that system works is what we are talking about. That is why a license is required and schooling to understand said system. I am most certain you have a license working in a dealer. It is not going to AUTO ZONE and dumping cans in a system. I was in the parts store this weekend and it was loaded with people buying FREON. Not one can or two they were buying like 4 cans and the counter prson wanted to sell them more. ((( WHAT ))) You know the ones with a low side gauge on the can. Normally one can is more than you need for top off. How can anyone know what a system is doing without high side readings. Anyway it is always great talk shop with you FOE Thanks

88 T/C Overheating only with A/C

Reply #37 – June 03, 2013, 05:56:31 PM

Geez Tom....good fix on the jeeps! Good thinking

Travis

P.S. as they say....not just a hat rack!

88 T/C Overheating only with A/C

Reply #38 – June 03, 2013, 07:05:23 PM

just to answer a few questions the car was 325 psi on hi side at idle 700rpm with all cooling fans on, i released the pressure (freon) from the high side valve to 230 psi . short drive and no overheat on highway, will have to wait at least a week for some hot weather to try on a longer trip as temps have dropped where i live.

88 T/C Overheating only with A/C

Reply #39 – June 03, 2013, 08:04:58 PM

I did 3 AC repairs today. And was thinking about your car. The S10 blazer i fixed ran a low side of 28 and the high side was 150. Vent temps were 38* and i was happy with that. Thinking about your high side numbers came to mind and it hit me. 86 was questioning or thinking of replacing his stock system!!! But you just proved that the stock system retrowed with 134A had that compressor pumping out almost double what it was designed to do with no problem whatsoever. Those old systems were really over BUILT. YOU PROVED IT THANKS.

Clearly your system was over charged by a lot. When you mentioned those high pressures i knew the system was over charged. No question in my mind about that. So as i always say people normally over charge systems. But in reality an undercharged system is always better than over charging. Glad you hung in and found the problem. Good Job!!! I think you are good to GO!!!

88 T/C Overheating only with A/C

Reply #40 – June 03, 2013, 08:25:38 PM

Just for the record if you are curious what i did to the JEEP for my mod

SIMPLE!!! I installed a DIODE on the clutch side contact of the AC CLUTCH RELAY. Then the other side to the pull in winding of the condenser fan relay. When the AC clutch was commanded on by the clutch relay the diode fed Battery to the winding of the fan relay. Naturally the fan ran every time the clutch was energized. The diode was necessary to prevent a back circuit. A 2 minute FIX at the relay fuse panel under the hood. The diode i bought at Radio Shack for a couple of bucks. The results were amazing and fixed the issue. The high side never went over 160 LBSG. The belt never squealed again i made tuns of money with a 2 dollar diode 2 minutes of work and laughed all the way to the bank. The local JEEP dealer sent me all his work on this issue and they were happy to pay me. Their techs were told by JEEP that the the system as designed by them was not to be changed and nothing was wrong. Well they were FULL OF IT. Thanks Tom

88 T/C Overheating only with A/C

Reply #41 – June 04, 2013, 12:47:20 AM

That's a sweet fix....great thought out process...but that is what makes u a great tech....then add a few years experience.

If I lived in CT I would be a customer... Its a rare nowadays. Just plug in the ODB2 and it will show us the way.
Good techs know better.

Travis

Im impressed!

88 T/C Overheating only with A/C

Reply #42 – June 04, 2013, 07:37:11 AM

To OP, go get professional AC service. Evac charge, the whole deal. be sure to remind them that it will take less refrigerant than is on the underhood label. Specify 2lbs 6oz to 2lbs 8oz. I don't know if that's how it went in the first place or if you charged it with cans, but go see a pro to make sure things are right.

88 T/C Overheating only with A/C

Reply #43 – July 15, 2013, 07:53:09 PM

Final post on this subject. After getting the hi side pressures down in a/c system it seemed to be ok it would run around 195 on the high way w/ ac on. A series of events alternator power wire fried towed home fixed it,car started running hot no ac on though i might have blown head gasket when i was trying to limp it home with battery dying, i'm boosted u get the picture loss of ignition fuel under load it could happen. Negative on gaskets,did plugs and finally did the T stat low and behold car runs cooler than ever once again proving i'm as stubborn as a ass maybe it wasn't as new as i thought. Car did start running like towed to buddys shop leading me to drop fuel tank feed line partially popped fixed it tried to start it starter locked up would barely crank than it started cranking and wouldn't stop, changed relay and starter had a spare,checked plugs they where done so was oil. While installing new plugs i popped a vac line I didn't like how it was rooted, it was full of fuel lol got a new diaphragm for the aeromotive reg and now shes running.changed the oil again as it was still contaminated. still wasn't running good I put a heat gun on all header tubes 1 was way colder put a old plug in it and temp went up, driving around with the a/c its at about 180 or less. Pulling injectors out next as i'm not pleased with the way its running its been a fun couple of weeks, just glad its not head gaskets.