Automotive HVAC Pressure Diagnostics

Automotive HVAC Pressure Diagnostics


[Music] automotive hvac pressure Diagnostics pressure analysis Diagnostics is the cornerstone of properly doing a climate control system assessment as we all know the HVAC systems is composed of a high and a low pressure side the orifice tube or expansion valve is the one components in between these two refrigerant can do it’s the compressor of course is the one in charge of pressurizing the refrigerant pressure analysis is by far the best and probably in many cases the only way to properly diagnose the dozens of specific issues with the automotive HVAC system but first here are the various scenarios relating to pressure analysis before we go into it it is important to understand what the baseline pressure should be the normal HVAC baseline is about 39 psi on the low side and about 250 psi on the high side how far away we divide from this baseline is what’s going to determine our issue here are the different analysis scenarios case 1 high pressure on the low side and baseline pressure on the high side this may translate to say about 125 psi on below and 250 on the high side and what can we ascertain from these readings actually quite a bit we’ll begin by starting our climate control troubleshooter software this is a cutting-edge HVAC analysis tool it’ll make our job of explaining a lot easier after starting the analysis software we choose our vehicle in this case of hypothetical Dodge then we choose from the tab is above in this case the pressure analysis there are other software section as well we are then alerted to use the up and down buttons to set the HVAC gauges and then press analyze for the results we now set the high pressure gauge to about 250 psi we then set the low pressure gauge to about 125 psi [Music] then we have analyzed here’s what the climate control troubleshooter says the expansion valve by the evaporator or the orifice tube located at the high side entrance toh the evaporator is faulty the pressure indicates a stuck open expansion valve or perforated orifice tube here’s why the suspect is the metering device which we call either the orifice tube or expansion valve the compressor generates the refrigerant pressure needed by the HVAC system seen here once the refrigerant reaches the orifice tube or expansion valve it changes state due to their restriction but in this case the restriction has broken or its aperture is bigger than expected the result is a balancing of pressure between the high and low side this issue is kamon regarding the expansion valve but less so on orifice tube systems case 2 very high pressure on the high side or higher than normal and low baseline pressure in the low side this may translate to 30 psi on below and 350 psi on the high side so hatch can we determine from these readings going back to our climate control troubleshooter we first reset the gauges and now set or ganja’s accordingly with a high side at 3 500 psi and the low side at 30 psi [Music] then we hit the analyze button here’s what the climate control troubleshooter says the AC expansion valve or orifice tube is clogged do not operate the AC system at such high pressures once the system refrigerant is removed do a thorough cleaning or replace them a Turing device now why do we come to this conclusion it is simple a clogged metering device like the expansion valve or orifice tube will in effect make the pressure go up and lower the low side as well this is the classical symptom of a clog in the system anytime the low side goes below Vasa line but with higher than normal pressures look for a clog in the pipes case three lower than baseline pressure on both the low and high side this may translate into 200 psi on the high side in 30 psi on the low side [Music] then we have analyzed here’s what the software says you’re low on refrigerant perform a full recovery and charge the system according to proper specs the system pressures on both sides is low due to less refrigerant being pumped in fie system this is by far the biggest issue seen on all automotive HVAC systems it is also fairly simple to understand in the event that the pressures are low across the board a low charge is the on line possibility even a weak compressor will tend to keep a low side higher due to lack of competing ability and a full recover and recharge should always be done to rule out the compressor in fiscals as you can see the ability to analyze a climate control pressure settings is instrumental in diagnosing the system a form of analysis software as seen here is also desirable at first and even just to double-check your own mental results of the situation in all cases knowledge of automotive HVAC in practice makes perfect [Music]


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