when the weather gets hot, you want to know that your car’s air conditioning will run the way it should. however, when there is a bad ac pressure switch, it can become difficult to cool off.
we look at the symptoms of a bad ac pressure switch and help you find the location. plus, our guide reveals how to test a bad ac pressure switch and discusses the possible replacement cost.
some of these symptoms are easier to diagnose than others. plus, there are a few ac system trouble codes that might lead you in the right direction. let’s take a look at the most common signs of a bad ac pressure switch:
the most common symptom of a bad ac pressure switch is a faulty or intermittent air condition function. in most cases, you will notice this during hot days when there is not blowing any cold air through the vents.
to find out how to solve the problem, let’s take a look at a more detailed list of the most common symptoms of a bad ac pressure switch.
bad ac pressure switch symptoms
1. intermittent air conditioning
this ac system symptom can show up in numerous ways. you might notice that the system starts up and cuts out for a short time. or, it might only work occasionally, leaving you hot most of the time.
either way, when the air conditioning only offers intermittent usage, it’s a good sign that the ac pressure switch is faulty. to become comfortable again, you will need to have the switch replaced.
related: 9 causes why your car ac is not blowing cold air
2. air conditioning stops working
what’s worse than the air conditioning working intermittently? how about when it stops working at all? if your ac doesn’t run, the refrigerant pressure switch sensor might be defective.
however, many components make up the air conditioning system, so your problem could be entirely different.
3. warm air is blowing
when you turn on the air conditioning, you expect to feel cold air pour out. however, when the ac pressure switch goes bad, warm air might be all you get.
however, this problem is also caused by low refrigerant levels, which should be checked regularly.
4. strange air conditioning system noises
if the compressor is clicking off and on, you are going to notice some strange sounds. it will sound like the clicking occurring when the compressor normally activates, except the air won’t work.
listen for the distinct clicking noises, telling you that the switch turns the compressor off and on.
related: 6 symptoms of a bad ac compressor
ac pressure switch location
the ac pressure switches are located on either side of the ac unit. you will find one switch on the high side and another on the low side.
the low-pressure side switch is found before the ac compressor, while the high-pressure switch comes after the compressor.
most ac pressure switches are found within the engine compartment, but some manufacturers put them elsewhere. a look in your service manual will show you the appropriate location for your model.
ac pressure switch function
the ac pressure switch function is to provide a safety monitor over the system. it is responsible for monitoring refrigerant levels on both the low- and high-pressure sides of the ac unit.
that’s why you have two separate ac pressure switches on your vehicle. one monitors the high-pressure side, while the other is evaluating the low-pressure aspects.
the low-pressure switch ensures that the pressure never drops too low. this problem is caused when a leak occurs. when the ac compressor pumps out refrigerant without the right pressure, it can cause significant damage to the compressor, leading to higher repair costs.
the high-pressure ac switch monitors any blockages in the system that would lead to more pressure. if the pressure builds up too high, there could be an explosion in the system. that’s why the switch tells the system to shut off power to the air conditioning, so no more pressure builds up.
as you can see, both of these switches operate as safety sensors, protecting not only the ac system but also you and your occupants from danger.
how to test an ac pressure switch
if you have some basic mechanical knowledge, you can follow these ac pressure switch diagnostic steps to figure out what’s going on.
1. turn on air conditioning
leave the engine running and turn on the air conditioning full blast. make sure you have the windows open, so the air doesn’t cycle itself.
the first sign that the air conditioning pressure switch is bad is when the system shuts off intermittently. this shouldn’t happen with the windows wide open.
2. feel the condenser tubes
pop the hood and look for the condenser. it is a grille-shaped or block component that connects to the compressor with tubes and hoses. it also contains a belt and pulley system.
feel both tubes coming from the condenser, moving toward the firewall. they should be cold to touch because refrigerant should be flowing through them.
if one of the tubes doesn’t feel cold, there is no refrigerant moving through the line.
related: 5 symptoms of a bad car a/c condenser
3. check ac pressures
use your air conditioning gauge set to check for adequate levels on both sides. you will attach the low-pressure gauge to the low-pressure fitting and vice versa.
on the low-pressure side, you should see readings near 30 psi when the temperature outside is 90 degrees or less. the high-pressure side should be around twice the ambient temperature with 50 psi added.
if the low or high pressures are off, there is a larger problem with the system.
4. scan for trouble codes
with the obdii port on your vehicle, you can use a code scanner to check for dtcs. you can also use the code scanner to erase codes once you repair the problem.
if you don’t have an engine code reader, consider stopping at your local auto parts store, where they might offer the service for free.
5. test electrical connections
take the pressure sensor off and test the connection heading to the sensor from the electrical harness. make sure your key is turned on to the accessories spot.
when the electrical connection is working as it should, the multimeter will read between 4.0 and 5.0 volts.
ac pressure switch replacement cost
the average ac pressure switch replacement cost is between $50 and $300. to buy the ac pressure switch, you will likely spend between $20 and $100, while labor can cost $30 to $200, depending on how difficult it is to reach the sensors.
crystal
how to find a leak in my toyota sienna mina van 2006
tyrone logan
i have a 2019 chevy impala lt with 52,000 miles on it. my ac compressor not get power and i took it to the chevy dealership. the r1234 freon that it calls for is good and the pressure. but the ac clutch not coming on to blow out cold air. so can it be the pressure switch that’s stopping the power from coming through.
warren bohler
my tahoe 2004 has been sitting for a couple of years.the acshows a high pressure.can't fill with 134a.it won't flow intosystem.blows warm air.could it be a high pressure switch?(ac not used for almost 3 yrs).thanks.
john
hi guys have a golf mk 1v and have power to ac pump but doesn’t work can you remove pump pressure switch without loosing any fluid
harold harvey a. mamhot
i have a honda civic 1995 model carb type. the or blem is this... if i on my ac first in the morning it runs perfectly then in the noon time when the weather is hot it will shot off then on and off. so i tried to move the connector of tge high presure switch then put it back then it turns again my ac compressor then a few seconds it wil turn off again.. so i decided to bypass tge pressure switch. my question is, is my preasure switch is bad or in the system.. second is.. it is safe to make the bypass of the pressure switch and i will manually turn my ac climate control on and off for it will not make the ac compressor always working for it is working effectively on cooling my car?
ron
on a 1993 ford ranger 4.0l 4x4 stx the compressor is not getting power from the clutch cycling pressure switch. i have voltage going into the switch. i applied 12 vdc to the compressor and it spins as it should the question i pose is what closes the cycling pressure switch, freon pressure or electrical? i don't want to replace a switch without knowing what makes it open and close.
sohaib
my car toyota corolla 2013 model compressor doesnt restart once it is shut and doesnt cool . the ac mechanic told it is due to problem in sensor as air ia sufficient and asked to replace compressor and radiator as sensor is not available in market. will it be helpful to change compressor or any other troubleshoot
aldas
no please, just look for the sensors on ebay, changing the c ok compressor won't solve the problem since the one you have is working already
mark
we're is the ac compressor relay located on a1992 buick riviera?
chris
can the compressor run if the pressure switch is going out?
zak
hi i have 2014 ford fusion 1.5 lt i charged my ac when i turn it on it builds too much pressure and does no cool at all please answer
minh nguyen
thank you 🙏 for great details. i like to know more with one four wires ac pressure switch. how do i know it’s bad?
terence
hey magnus i just recently changed compressor ,expansion valve and dryer on my 2009 honda civic, and the ac is still. not cold,plus i have fluctuating on the idle,please help
joe
2017 ram 1500 , a/c intermittently stops blowing cold . took it to ram, they say nothing is wrong.. next day, did it again... took it in, same thing, nothing wrong .. it blows cold for an hour or two then goes warm.. any ideas?
vh das
ensure, the condenser fan is running without which the temperature of condenser goes above the permitted level after one hour or so depending on the ambience temperature of the place and the high pressure safety switch shuts off the compressor to avoid possible explosion of the condenser
cindy lopez
hi magnus, i have a 2003 saab vector my ac comes on for about a minute then it turns off. the compressor comes on when you turn on the car then it stops working after a minute. any advice. thank you
kenny
hi i have a 2019 f240 xlt 6.7 can’t find the condenser for the low pressure switch
paul
hi, if without ac pressure sensor, will the compressor still turn on? thanks
joe
2003 toyota 4 cyl. camry. interior a/c light was blinking and magnetic clutch was not actuating. first checked the relay and fuses and were all good. removed negative cable from battery when checking wiring. when putting negative cable back on, the a/c clutch actuated, a/c clutch engaged and engine rpm's went very low stalling the engine. after re- starting the engine, the compressor clutch stayed engaged and the engine returned to normal rpm's. the compressor is now engaged, turning freely without any strain to the engine. checked the freon pressure on low side and it is very high (buried the pointer in the red). light on the inside is still blinking, no a/c and no voltage going to the switch on the compressor. question; is there any chance that the compressor is still good and not working because of a short somewhere between fuse box and switch atop the compressor?
jim tuohey
where is the a/c low pressure switch located on a 2010 corvette grand sport? (ls3 engine) is it difficult to replace?
raj singh
my engine fan stays on all the time regardless of the temperature. as soon as i turn on the ignition the fan comes on.. any ideas,? i have one switch that control the ac compressor and the fan. toyota corolla nze
tony l martindale
i'm having the same problem with my gmc sierra
shabz
bmw x5 e70 -2009 when i initially start my car in the morning, my ac gives hot air. later when i accelerates with an rpm 3 or more for few seconds it gives chilling cold air. is it can be the issue of pressure switch ???
jeff
hi magnus. great website! thank you! car: 2012 honda jazz hybrid, gp1, cvt transmission. ac was blowing warm. shop put on gauges,: lo side 30, but high side 400.... told me i have a blockage but didn't know where, suggested i clean out condenser fins. i did that, then i put a can of dye leak detector on low port, and within a minute the pressure relief on back of compressor blew! i thought i would try to diy change my: hi/low pressure switch, compressor, condenser w/drier, and the (difficult) expansion valve on the evap, to cover all bases. (if you think only one or two of these parts is the culprit, let me know...) q: what is the difference between compressor trse07 and trse09? i can't find the answer. also, which one does my car take? thanks! jeff
willy
my compressor clutch kicks in when i turn on the a/c. problem is there is no pressure in the system. it has been evacuated. bad compressor? high, low pressure switches?
danny ritchey
my ac compressor isn't working,i bought a new one and replaced it,and i made sure the refrigerant is good ,i checked the fuses the only thing that i can think of is the pressure switch .any other ideas would be appreciated.
jeff. lantrip
i'm have 2002 honda odyssey, i have been working on,compressor is working system is charged,its not cycling on and off , everything is seem to be working,all the control are checked out in the cabin,but not cooling, i am baffled as to what the problem is help!! please!!
brian
a/c cutoff switch on back of the compressor , or could be low pressure switch , you need to have some a/c gauges to see what is going on with it
mike
first, did you check the ac relay? you can usually swap the horn relay with the ac relay to test if its bad. this is pretty common on the honda vehicles. i had an odyssey and the relay was fine, ended up being a bad $15 electromagnet in the clutch. it wasn't easy to replace while still on the vehicle but it can be done.
james risley
is there a such thing as a triple pressure switch, does this relate to bot high, and low side a/c pressure switch? i cannot locate a low side pressure switch? hyundai santa fe 2005 v6 3.5 thank you!
ray ray
nope, there's only one pressure sensor
mark
i own a 2000 chrysler concorde 3.2. are there 2 switches on my car? i replaced the low side, but can’t seem to find the high side switch?
durga
hi friends, my hyundai getz 2008 is not blowing cool air. i took the car for repair in auto master and charged $145. next day it was not working again. requested for further correction but they failed. i have checked the fuses and control switch, it is found ok. checked power to the compressor and it’s missing. now i have no idea. can you please suggest and guide me to solve the problem