1991 PA Ultra A/C goes into Econ mode

[HotZ28]

13 or 113 - In-Vehicle Temp Sensor circuit open or shorted.

The 28 PSIG line intersects the (average) of the Frigc & Freezone/Freeze 12 curves at about 40F. Adding the 10F evaporator drop, means that the duct temperatures will never get below about 50F for FRIGC/Freezone/Freeze12, or about 10F warmer than with R12.

I would assume, if you have both pressure sensors shorted, the in-vehicle temp sensor would take over the control and give you a code 66, due to low or high temp. If I were you, I would get the Duracool R12 out of the system, then convert it over to R134 and send the Dura cool back to the camel jock!

[JoeNezz]

Yes Gocart879 it sounds like you have a freon leak, Don't try to do it your self you will just make things worse in the long run & end up spending more money to repair it.
Don't try any of those quick fixes like leak stop, unless you plan on scrapping the car soon as they can cause more problems than they solve.
also it is illegal in Canada to mix refrigerants so if your system does contain R 12 freon it will have to be removed by a licenced A/C mechanic before they can add another type of refrigerant.
If your system was topped up last year bets are that it has a small leek probably cracked O rings.
In Ontario Canada it is Illegal to top up a system containing"R 12 freon" they must leak test & repair any leeks before they can add R 12, however I guess it is not Illegal here for them to use HC12a as most A/C service centers use it as a direct low cost drop in for R 12 or R 134a.

If the car is in good condition & you plan to keep it for another 3 to 5 years concider getting the leaks properly repaired & getting a conversion from R 12 to R 134a as R 12 sells at bootleg prices & trying to find pure R 12 is impossible in my area.

Try to find an A/C service centre in your area with a good reputation, take it in for an inspection & leak test, then talk to the mechanic about your options. just keep in mind you only get what you pay for ,if he says he can fix the leaks & charge your system for under $100.00, chances are he will probably just put in a can of " pro seal" or some other leak stop product, give it a shot of refrigerant & send it out the door.

Hope I was of some help,
Roger

[JoeNezz]

well back to my problem, thismorning I jumped out the fan pressure sw figuring maby the PCM monitors the fan cycles to check for low charge, but no luck, she ran great then switched to econ once the engine warmed up.
I guess the next thing is to see if I can find a used PCM at the scrap yard at a good price & sub that & see what happens as I do not want to play around with my PCM & screw up the drivability of the car by shorting somthing out.
As my guess would be cold solder connections on the PCM board if its anything like the "oil monitor" & "HVAC programmer boards" that I had to re solder most of the connections to solve intermittant problems.

[HotZ28]

FYI:
The EPA's ban on R12 production gave rise to a new generation of refrigerants. Now, blended versions of alternative refrigerants are wreaking havoc on vehicle A/C systems and shop equipment.

The windshield of a Lexus sedan hurtles across the hood of the car. All four side windows shatter, producing a shower of tiny glass fragments. Flames engulf the dashboard and sweep the head of the mannequin behind the wheel.
This fire erupted because the Lexus' air-conditioning system was charged with HC-12a, a refrigerant (produced by OZ Technology in Idaho) that contains propane and butane gas.

The incident occurred during an event staged by the Palm Beach County Fire Department and the International Association of Arson Investigators, who demonstrated the dangers of replacing high-priced CFC-12 with cheaper, flammable substitutes--and illustrated the importance of using only refrigerants approved by the U.S. Environmental Protection Agency.

The EPA's 1995 ban on R12 production gave rise to an alternative refrigerant market--and to a problem for the automotive service industry. Ten approved substitutes are now available, but problems arise when these refrigerants--and/or Freon--are mixed within an A/C system. Combining refrigerants leads to cooling and operating problems, eliminates the opportunity to recycle any R12 in the system, taints good supplies of R12 already in shop tanks and contaminates recycling/recovery equipment. The substitute HCFC-22, commonly known as R22, causes additional problems because it destroys and leaks past A/C system seals and hoses, sometimes leading to plugged refrigerant circuits, reduced refrigerant flow and damaged components.

These problems are costly, but they are minor compared to the dangers posed by refrigerant alternatives or mixtures that contain flammables such as propane, butane and isobutane. Even more frightening is the fact that such cases of contamination are not rare. Even though the EPA prohibits the use of HC-12a in automobiles, OZ Technology President Gary Lindgren told a television news reporter from Phoenix that more than 5 million vehicle A/C systems operate on the refrigerant.

Overall, industry experts estimate that 31.5 percent of automotive A/C systems are contaminated with combinations of R12, HFC-134a, R22, hydrocarbons, propane, butane and isobutane. Neutronics Inc., an Exton, Pa.-based company that manufacturers refrigerant identifiers, predicts that 10-12 percent of vehicles serviced this summer will be contaminated. And because few automotive professionals or consumers are aware of the problem, that percentage is expected to increase.