In dash thermometer reds REALLY high, 30 dagrees out side it reads 90-125

Sounds like you need a new thermostat on the engine. There is no thermostat in the dash, only a gauge.

For charging purposes, you really should be monitoring the low side pressure. Depending on ambient air temperature, the low side should be between 30 and 50 lbs PSI. The high side can be between 135 and 330 lbs PSI.

The high side should read a little more than 100 pounds plus the ambient temperature. On a 100 degree day the high side will be over 200 pounds. A high side reading of 250 pounds is no problem. The important reading is the low side, and it should always be about 30 pounds. Higher than 30 will produce warmer air, and under 30 will cause the evaporator to freeze up.

BOTH High and low readings should be checked to have a better idea of what is going on with an AC system but based on the limited information… the compressor is not engaged or is not pumping. Below are some things I would check;

1. Check the high and low gauge readings with the AC on & set on MAX/Recirculate, middle vents with the engine at 2,000 RPM’s, blower speed on high.

2. Check the vent temperatures with a thermometer from the middle vents, far right & far left vents?

3. What is the outside temperature at the time the readings were taken?
4. Check to see if the condenser fan blowing strong?

5. Notice if compressor clutch is cylcling excessively.
Could be overcharged, not enough air going across condenser fins, compressor not pumping sufficiently… BOTH gauge readings are really needed to get a better idea.
Below are normal car AC pressure readings with 134A.

Normal readings on high and low side with AC OFF (static pressure) – Depends on outside temperature, but normally is between 80-105 PSI

Normal low side reading with AC on high speed and MAX & engine at 800-1000 RPM’s – Ranges from 25-35 PSI

Normal high side reading ranges from 200-350 PSI

Don’t assume that if adding little Freon is good that adding a lot is better! Overcharging just a little can decrease the performance of the system and possibly damage the compressor

Thank you for using fixya and good luck, keep me posted. Be glad to help you get your A/C running again soon.

common for the 4WD switch it self to go bad, what happens is the connection in the switch solider goes bad from the heat and current draw from the light. Inspect the switch and repair any signs of damage or replace the switch in the dash.
Below are normal car AC pressure readings with 134A.

• Normal readings on high and low side with AC OFF (static pressure) – Depends on outside temperature, but normally is between 80-105 PSI
• Normal low side reading with AC on high speed and MAX & engine at 800-1000 RPM’s – Ranges from 25-35 PSI
• Normal high side reading ranges from 200-350 PSI

Don’t assume that if adding little Freon is good that adding a lot is better! Overcharging just a little can decrease the performance of the system and possibly damage the compressor

BOTH readings should be checked to have a better idea of what is going on with an AC system but based on the limited information… the compressor is not engaged or is not pumping. Below are some things I would check;


1. Check the high and low gauge readings with the AC on & set on MAX/Recirculate, middle vents with the engine at 2,000 RPM’s, blower speed on high.


2. Check the vent temperatures with a thermometer from the middle vents, far right & far left vents?


3. What is the outside temperature at the time the readings were taken?


4. Check to see if the condenser fan blowing strong?


5. Notice if compressor clutch is cylcling excessively.


Thank you for using fixya and be safe

You may not have enough R134a in the system, or you have over charged the system and your high pressure switch is turning your compressor off when the pressure get's to high.
You really need a A/C gauge set to see of your system is over or under charge. If it's under charge, that's good. A over charged system will cause your a costly repair of replacing a $300.00 rebuilt compressor plus the vacuuming out the system and replacing the accumulator which may have parts from the compressor (bearing).
Normal readings on high and low side with AC OFF (static pressure) – Depends on outside temperature, but normally is between 80-105 PSI
Normal low side reading with AC on high speed and MAX & engine at 800-1000 RPM’s – Ranges from 25-35 PSI – Note that on many Chrysler products a normal reading on the low side may be 15-25 PSI
Normal high side reading ranges from 200-350 PSI
Could be overcharged, not enough air going across condenser fins, compressor not pumping sufficiently… BOTH gauge readings are really needed to get a better idea.
Don’t assume that if adding little Freon is good that adding a lot is better! Overcharging just a little can decrease the performance of the system and possibly damage the compressor, assuming the blower speed is on high, AC is set on maximum and engine is around 2,000 RPM’s

1. Check the high and low gauge readings with the AC on & set on MAX/Recirculate, middle vents with the engine at 2,000 RPM’s, blower speed on high.
2. Check the vent temperatures with a thermometer from the middle vents, far right & far left vents?
3. What is the outside temperature at the time the readings were taken? 4. Check to see if the condenser fan blowing strong?
5. Notice if compressor clutch is cylcling excessively.


Thank you for using fixya and good luck

I would guess the outside thermometer has lost its calibration.
Does it seem consistently 5, 10 or 20 degrees off all the time?
Let me know.
Regards,

my thermometer is blinking -40 degrees how can i fix this

Hi! The problem you are outlining is very similar to the Rover V8 (Buick engine). We Brit's are used to the low oil pressure when warm. I presume a complete oil change engine flushed with new replacement filter has been carried out? Maybe a top quality synthetic oil with additive may help. You may take it a little further and replace the oil pump with an after market performance up rated one. If you really are worried about low oil pressure damage whilst in low rev's try Molybnenum Disulphide an oil additive which really reduces friction metal to metal wear particulary in the situation you are describing.
That's the best I can suggest at this moment.
Good Luck! and Happy New Year!
Paul 'W'
Onyer~EDson(:0)~[><

Clean the Idle Air Control Valve. It's on the throttle body below the Throttle Position Sensor. Worked for me! Good luck.