Outside Compressor High Pressure Reads 150 and Low Pressure Reading 15, Units Blows Hot Air

March 02, 2022 Post a Comment

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car a/c ducts

Automobile Air Conditioner Bravado Warm Air, Non Cooling

Is you motorcar's air conditioner blowing warm air merely and no cool air? Your A/C cooling trouble could exist caused past any of the following:

Your A/C system may have lost its charge of refrigerant. This is probably the most mutual cause of a no cooling trouble. Another possible cause of no cooling may be that your A/C compressor is not be engaging when you turn on the A/C. This tin can be caused by an electrical mistake in the A/C compressor circuit or the magnetic clutch that drives the compressor. Another crusade could be an internal obstacle inside the refrigerant circuit that is preventing refrigerant from circulating inside the A/C system. Some other possibility might exist a blend air door inside the HVAC unit that is stuck in the Heat position and is preventing air from flowing through the A/C evaporator.

Compressor Checks

Start with the compressor. Does it engage when you turn on the A/C?

If so, the compressor is working and the A/C system probably contains enough refrigerant to make cold air, so the trouble is inside the HVAC unit. Replace the motor that controls the blend air door (this is a difficult job and all-time left to a professional person since it involves tearing autonomously the HVAC unit -- about an 8 to 10 hour job!).

If the compressor does not engage when you turn on the A/C, see if information technology volition run by jumping the compressor clutch wire directly to the battery (apply a fused jumper wire). If the compressor works when you spring information technology, and the A/C blows common cold air, the system contains refrigerant and the fault is likely a bad A/C compressor clutch relay or a bad clutch cycling switch or pressure switch.

If the compressor does not engage when you jump it, the problem is a bad compressor clutch.

If the clutch engages merely the compressor does not turn (the chugalug will first to slip and squeal), the compressor is locked up and you need a new compressor.

If the compressor clutch engages and turns the compressor, merely the A/C still does not blow cold air, the system is probably low on refrigerant and needs to be recharged.

Refrigerant Checks

Connect an A/C pressure gauge to the HIGH SIDE service port (located in the high pressure hose that runs between the compressor and the condenser in the forepart of the engine compartment). The gauge will tell you if in that location is any pressure level in the system. Simply depressing the service fitting valve with a pocket-sized screwdriver to see if whatsoever refrigerant squirts out is NOT an accurate check because information technology tell you lot how much pressure is in the system. It may withal take some pressure only not enough to trip the low pressure prophylactic switch so the compressor will engage.

If your A/C system is low or out of refrigerant, bank check for leaks, then accept the A/C organization vacuum purged to remove air. Afterwards the air is out, it can be recharged with the specified amount of refrigerant. Information technology is important to get any air out as this will reduce cooling efficiency and may make the compressor noisy.

A/C Organisation Functional Checks

If the refrigeration circuit seems to be working (refrigerant in the system, compressor running and building pressure), just at that place is still no cooling, the trouble might be an obstruction in the orifice tube (located in the loftier pressure hose between the condenser in the front of the radiator, and the evaporator located in the rider compartment). A blockage hither volition forestall the refrigerant from entering the evaporator or recirculating through the refrigeration excursion.

If the orifice tube is plugged, the high side pressure reading will be lower than normal, and the low side reading will also be lower than normal considering no refrigerant is circulating through the system.

If the refrigeration excursion seems to be functioning normally (compressor running, frost or condensation on the high pressure line from the condenser to the evaporator), but no absurd air is blowing out of the ducts within the car (and the blower is working), the error is likely a BLEND AIR door that is stuck in the Estrus position, or possibly a badly chock-full cabin air filter that is restricting airflow. Some other possibility would be a fault in the automatic climate command system such as a ad interior temperature sensor or command module.

My advice to you if you know nothing most A/C service is to find a repair store that specializes in A/C repairs and permit them diagnose and repair your air conditioning cooling problem. Today's A/C systems with automated climate control are very complex and crave special tools and know-how to diagnose and repair.

This air conditioning diagnostic chart shows typical Low and High side gauge readings, and duct temperatures for common A/C cooling bug.

A/C Approximate Readings

To determine the Loftier SIDE and LOW SIDE pressures within your vehicle'south ac organization, you need an A/C Gauge Prepare. The Gauge Set must exist connected to the A/C service ports on vehicle to read the pressures while the system is running.

With the engine OFF, connect the A/C Gauge Set High Pressure Hose (the one with the larger coupler fitting) to the High Side service port (usually located in the compressor output line that goes from the compressor to the condenser). Connect the Depression Pressure Hose (the one with the smaller coupling) to the Depression Side Service port (usually located on the accumulator, or on the suction hose that goes from the evaporator to the compressor).

Start the engine, turn on the A/C to MAX, and rev the engine to 2000 RPM. Concord the engine speed and note the High and Low side pressure approximate readings.

NOTE: High and Low side pressure readings will vary with ambience temperature and humidity. The higher the temperature and/or humidity, the higher the gauge readings.

With late model R134a systems, practiced high pressure readings should range from 150 to 220 PSI at fourscore degrees F, 170 to 250 PSI at 90 degrees F, and 195 to 280 PSI at 100 degrees F.

A High side pressure reading of less than 150 PSI indicates a low accuse or a compressor problem. A high pressure reading over 300 PSI would indicate an overcharge condition (too much refrigerant in organization) or a restriction in the high side.

Proficient low pressure readings with R134a should normally exist in the 30 to 35 PSI range. If higher, there may be a low side restriction. If the reading is lower, the system may be low on refrigerant.

With older R12 A/C systems (1994 model year vehicles an older that have NOT been retrofitted to R134a), the HIGH side pressure readings will typically be 150 to 185 PSI at 80 degrees F, 175 to 205 PSI at 90 degrees F, and 200 to 250 PSI at 100 degrees F. Normal Depression side readings with R12 should be around 20 to 30 PSI for an expansion valve system, or xv to 40 PSI for an orifice tube organisation.

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