what causes low side ac pressure too high

My ac builds up pressure to about 100 psi on the low side, which causes the compressor to kick off. So, open the hood of your car and check the condenser and the surrounding area for any debris or blockages. If it is open all the time, then the compressor is pressurizing the entire system, which would cause the low side to go high until the pressure switch kicks if off. In other words, the cycles are moving out and in too quickly, which cause these high readings at the low side. Re: High 'Low-Side' Pressure Post by Cusser » Sun May 10, 2020 10:56 pm Howie T wrote: The fans respond well enough to the dashboard control (significant increase in fan noise with each increase) but not much air seems to be blowing through the vents, certainly not as much as I … If its cold out the compressor will run for a little bit, but if its warm out the compressor will not even kick on. Is it an R134A or R12 system? My hypothesis was that the car is 10 years old and may just have over time become low on refrigerant. Refrigerant is undercharged; Excessive condenser water flow; Condenser outlet water temperature too low; Air conditioner unit is over capacity; Ineffective compression of compresor or valve is damaged; Ambient temperature too low; Low Pressure Side Too High. Note: The most ideal pressure readings are around 150 high and 30 low. Add more refrigerant to low side with ac at full blast . In this case, the high pressure side would continue to have a high reading, and the low side pressure will continue to drop. After checking that my car does indeed use a R-134a based system, I purchased a canister of refrigerant with a hose and gauge for connecting the canister. If you are dealing with this issue, it would be because the compressor is cycling incorrectly. Probably just running low on refrigerant. Checking the condenser for blockages or debris is a good start to figuring out why the pressure is too high. watch pressure low side go to 35 and high to about 225,you are done. Standing pressure actually makes me go back to the expansion valve being bad. After changing the compressor, condenser, accumulator/drier, orifice tube and the rear expansion valve the mechanic says that both the low side and the high side pressures are too high. Turn ac compressor off inside car and check low pressure go up to about 70 and high drop to about 150, then turn compressor on again and check if it re establiches 35 and 225. Warning: Remember, venting 134a refrigerant into our atmosphere is illegal and bad for our environment. High Pressure Side Too Low. In general, it is not common to have a high reading with low side pressure reading and the normal one with high side. If R134A, check the pressure on the low side end (Black or blue cap on the line close to the evaporator , the line runs towards the radiator to the condenser), The AC should be on Max with the fan on high for at least 3 minutes, and you should have an optimal reading of 45psi. It also fits with the earlier symptoms of the AC randomly not working before it went out completely. Refrigerant is overcharged; Expansion valve is oversized Dirty or high-MERV filter: Having a dirty air filter or one with too high of a MERV rating can also cause high static pressure at the return air intake. He says the low is 80 and high is 375 and will go to 450. The following table presents the possible inferences and the actions that can be taken, based on the level of pressure registered by the high and low pressure gauges: Start car and check both low and high readings. We recommend using cheap, low-MERV filters and changing them monthly to prevent this problem. Granted it is 100 degrees here in Arizona. 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