Symptoms of a stuck open thermal expansion valve.

[@carlosruiz6179]

I just replaced the compressor, expansion valve, filter drier and condenser along with a flush on my Mitsubishi Outlander yesterday and I was having those simptoms just cool air and compressor was not shutting of on ac high. The low pressure line was getting cold all the way to the compressor and I knew something was wrong. Today i replaced the expansion valve for the old one and oh boy it solved the problem. Ac is super cold now and compressor kicks on and off like it should. This is the first time I do something ac related without any background and i find myself in a situation with a faulty new expansion valve. I wish i had seen your video earlier to avoid the head scratching I had to go trough. This is exactly what my readings were like.

[@TheDanbulance]

I've never had the pleasure of dealing with a failed expansion valve. Thanks for the run down.

[@jinnnguyen7077]

@6:07 that's a great analogy for how the expansion valve functions

[@gflores7018]

Awesome symptom to know , thank you Keep it coming

[@wilhelmhackenberg1210]

Is there an audible sound to a failing/failed expansion valve or evap core. 2nd gen tacoma. Fan on low or mid then turn on ac while on max ac. Hissing sound coming from the general area of the expansion valve. Compressor visiblely works, can see it turn on with ac switch. Thanks!

[@theoffroadingmechanic]

The hissing means you're low on charge as there's not enough refrigerant to compress to turn it into a liquid so all your compressor is doing is just moving a gas and that's what the hissing noise is. So what's going through your expansion valve is a has to a gas rather than liquid to a gas. You may have 80 psi in the system on the gauges but doesn't mean you have a full charge. And that can still turn on your compressor.

[@jharrison6557]

A stuck closed TXV will be normal to low on the low side and low on the high side. The txv becomes a restriction on the high side and doesnt feed refrigerant to the compressor

[@JD-sc7bd]

I hate ac problems nice video

[@americanpatriot5836]

Great video

[@FixIt1975]

Nice diag. I'm still trying to wrap my head around kilometers and kilograms as we're probably the last country on earth not on the metric system, here in the states. I can't think of another country that isn't, but I could be wrong.

[@d46512]

Canada uses freedom units in industry and commerce but not in government. The metric system is also ubiqutous in science.

[@charliemagoo7943]

Ummm low side is big line not the little hole as pointed out

[@mr.octavias]

It’s just me or am I seeing a straight cut on low side ac line at 4:26?

[@photondebuger45]

Mate maybe you can help me out here, im doing ac work on a 98 sonoma with the 2.2 in it. Now looking at the high and low sides on it has a vot in it a variable orifice tube in it. The low side is like about 35 to 40 round there and the high side was at lkke 150~ to 200 psi but the needle on the high side flutters. It also struggles to get up to 200 and keeps fluttering the low side stable as a rock at 34 to 40. The fan in the engine bay is indeed working i would say, its a thermal fan spun by the accessory drive too. I see it that its working because well the high side would rocket up it wasn't. Oh the truck reaches operating temp too. Thats steady too for the coolant temp. Tho im only getting like 58 degrees out the dash vents and actually gets worse (and i think because its the set up its a always on clutch and a variable orfice tube) im kinda torn if its the compressor or the condenser not working right what it could be. Oh this might help a little but i guess i can mention it, the compressor makes a ton of racket when its on. I also dont think it really should sound like that but im comparing it to other cars than an old gm truck and cars so i don't know how it really should sound. The fluttering guage on the high side like threw a caution to me as not being too right for it. What do you think.

[@theoffroadingmechanic]

So what is the issue not cooling? Pressure doesn't really mean anything if you don't have the correct amount of refrigerant in it.

[@photondebuger45]

@@theoffroadingmechanic oh it's filled properly I'm positive about that.

[@theoffroadingmechanic]

Not too familiar GMC HVAC system but does your HVAC controls for heating and cooling setting are controlled by vacuum for temperature? From what I'm getting you have good difference in pressure your high side might be higher on a hotter day your fan is cooling so your high side lowering the pressure and is normal.

[@photondebuger45]

@@theoffroadingmechanic I still am not too like thrilled how the ac compressor is making racket and it's already like in the mid 90s in temp here. Oh the blend door is the only one that's electronically controlled, the mode doors are the ones that are vacuum operated. The ac system funny makes the truck that's gasoline right sound like a diesel truck. I noticed that well it can climb up to 200 but after then drop again. I've done like both a TXV system and an orfice tube system but this one from the GMC here is real quacky. Mostly because it's a variable compressor a v7 style it is, and has a variable orfice tube too. Not sure if you've heard at least one of those trucks ac compressor if it's supposed to make noise or not lol. Also the flutter in the high side I never seen that in an ac system, yet possibly. A guy on KZbin said that the pt cruiser is like that too.... Never seen that and there's three in the family that I work on all of them the clutch never is always on like the Sonoma and they cool perfectly on a very hot day temps in the vents are 45 which feels fantastic too. My truck got to that and better and now not any more.

[@theoffroadingmechanic]

I have dealt with variable compressor the solenoid changes the angle of the swash plate in the compressor. But only worked on just txv. Wonder if one of the pistons detached itself from the plate in the compressor and just banging around. And giving you fluttering high side cuz it's not doing anything.

[@HereWeGoSteelers]

If you have a slow freon leak which you trace back to the expansion valve do you add any PAG oil back when recharging the system? If so what is a safe amount to add back? The more I look online the more confused I get. Thanks

[@theoffroadingmechanic]

The txv doesn't really retain any oil it's just a restriction for the high to low side. Unlike the other components that will retain oil and there is a specific amount to put back in for each component in the shop manual. But generally speaking if you're recovering the system with a machine I put back 1oz.

[@sivucit]

Hi, quick question, for stuck open expansion valve, why is low side not showing high or going up alll the time, bcz it is stuck open all the time, any reason behind that. 2. you also said if condensor is blocked, the high side will be cold, is that because condensor will act like a metering valve that why anhything after that condensor blockage will be cold to touch.?.

[@theoffroadingmechanic]

Depends what position it is stuck open as it changes in temperature. I have a video when the condenser is plugged it acts as like a orifice tube and it meters the high to low pressure it's not any significant of cooling but it shows on a thermal imaging camera.

[@joshuatran3667]

Hopefully you can help me. I did an AC job on my car about a month ago. Replaced compressor, drier, and expansion valve. My electric cooling fan was not working at the time. So i proceeded to refill the refrigerant. I got cold air but my high side preasure was increasing up to 300-400 psi and the hose wS really hot. As i was standing there pondering the cause, a loud pop happened and a fine hissing mist of refrigerant plus oil was spraying up in the air. Quickly i shut off the AC and freaked out. Eventually the high side pressure went down and the hissing stopped. I rechecked the system by disassembly and found everything was still intact. Re-pressurized the system with air and it held. Vacuumed it and refilled but i am afraid to run the AC at this point. I believe the pressure release valve on the compressor popped. What was the cause for my over pressurized high side? Could it be that i inadvertently put refrigerant into the high pressure side? Or could it be that i didnt have a working cooling fan? I did the same job on another car and had no problem.

[@theoffroadingmechanic]

The excessive pressure is due to your cooling fan not working the fan has to cool the compressed gas into a liquid which is why a condenser is called a condenser. And also why your line is getting really hot that high pressure is just the relief on the compressure to protect your system from over pressurizing. If you have a strong enough fan put it in front of the condenser and you will watch that pressure come back down.

[@joshuatran3667]

@theoffroadingmechanic Thanks. That was what I did on the second attempt. I put a Leaf blower in front of the condenser and saw the high pressure side went down. So if your fan doesn't work, you are stuck in a traffic jam, hot weather and you run your AC, are you going to risk your system blowing up like mine?

[@parvulucian9599]

I think I have the same problem with my 2014 Renault Clio AC system. The problem is intermittent. Usually it is not blowing cold when I come to a stop. But not always. The weird thing is that, if I completely stop the AC by turning off the cabin blower for about 30 seconds and then turn it on again, the air is cold once again. And the car is still at idle. Another thing I noticed is that, if I rev the engine at 2000 rpm or above, the car being stoped and the AC starting to blow hot, after approximately 30 seconds of 1 minute it recovers and starts blowing cold again and is blowing cold until I come to another stop and so on. The condenser was replaced one year ago so I guess it is not clogged. The fan is working fine. It run at first speed if the outside temperature is not to high and at second speed if outside is above 30 degrees Celsius. Now, nobody I asked could answer why my AC is acting this way. Could it be the expansion valve is also stuck open? I incline to think so but I cannot explain why it recovers and starts blowing cold again after I turned off the blower for about 30 seconds to 1 minute.

[@utube5361]

Hi, hope you can help me with some advice. I have a 2011 Ford Fiesta 1.6 with 14k miles on it. And the car is not used frequently. I'm from Indonesia where the outside temp is quite hot all the time, Lately i noticed whenever i started the engine at idle, and then started the AC just to get it work for some time, the compressor won't cycle OFF at all like what it should be before (last time even waited till 30 minutes). The blowing air from the AC is also ok (cold), so what do you think is the common problem for that. When the engine is off, I can rotate the clutch freely by hands. The low side line is also sweaty as it usually should be Someone hooked up the gauge on the low side, it was reading about 25-28 psi. I don't want to bring it to some shop without knowing first at least the base of the common culprit, because i'm afraid they just misdiagnose it. Thank you

[@theoffroadingmechanic]

To understand how your a/c works and what will disengage the compressor clutch either the thermal protection switch on the compressor, a/c pressure switch will switch off the compressor below say 10psi or above 500 psi roughly., and the temperature probe on the evaporator to prevent icing/freezing. These are the things electrically to cut off the compressor from engaging. What you think is an issue may just be normal operation because if your outside temperature is hot and you're using outside air instead of recirculating the cool air already in the cabin that temperature probe won't see it reach that temperature that's going to shut the compressor off. There is a difference on what your a/c does depending on if your using recirculate or not. If you have a thermal expansion valve mechanically it will control the amount of cooling by metering the flow depending on temperature as well. And if you have the newer style of compressor where it does not have a clutch and it has an internal solenoid that controls the compressor internally that's a whole nother thing. Usually when someone complains about there a/c it is usually about it not working not usually that the compressor is not kicking off since it may just be normal operation. If I were your I wouldn't waste your money on having a shop try to figure out this "problem" just so your not being charged for something that may not be an issue especially in hotter climates. On the Honda the compressor clutch will cycle on and off but will also stay engaged depending on temperature. Hope this helps.

[@utube5361]

@@theoffroadingmechanic I always set it to "recirculation" inside the cabin and never allow the outside air to flow inside. So the cabin temperature should be more "kept". But if the compressor keeps running all the time without cycling off, could that work load damage the compressor ? By the way, just curious, if i set the temperature to red (heat zone) to warm up the cabin, is the compressor still running / used for that or the compressor will disengage and not used right from the first time we set to hot temperature ??

[@theoffroadingmechanic]

It would be quite the opposite less wear on the clutch, less of an electrical load since it takes more current to engage the clutch than it does to hold it. Same as when starting the compressor back up over and over again than to maintain it. That's why a lot of new cars now are going to clutch less style compressor and is just controlling solenoid in the compressor to increase or decrease pressure. Your compressor can be disengaged while your driving but not even know it since you won't feel it or hear it since it create more pressure at higher rpms but not at idle. Something I forgot to mention but that will be the job of the pressure sensor and the temperature probes job. Some sports car such as the civic si in the manual it will say that it is normal for the a/c to stop blowing cold at wide open throttle because of the power demand if your racing your si. Your modern car a/c does more than just cool, it also acts as a de humidifier so you can have hot/dry air as well as cool dry air to help defrost/defog your windshield. Or for temperature control in the auto settings

[@Bruce_Wesley]

How many labor hours did you quote to replace the expansion valve?

[@theoffroadingmechanic]

Quoted 2.4 for the expansion valve plus recharge.

[@theboxingreviews]

nice video. almost same problem I encountered with my car ac system except that the lowside pressure reads really high even reaching the retard level. is it still the stuck open txv that is causing this reading?

[@theoffroadingmechanic]

Do you know how much refrigerant is in your system could you possibly have a way over charged system?

[@vincentgonzalez307]

Brother, My 2007 SI is not getting power to the AC compressor and fans are not working, I checked all relays and fuses all are good. Do you have any recommendations on what else to check? Thank you.

[@theoffroadingmechanic]

Do you have a scanner? On live data under engine there won't be an HVAC module since it's to hold to have that but you will see a couple of pids like a/c pressure and the a/c button and the commands for the high and low speed fan that's all the information you will have there there is a diagnostic function where you hold the defrost and recirculate and it will flash you some codes but all that does is just check for open circuits. See if the pressure and is the pcm seeing the a/c button on, on live data show on. The pcm controls the relay for the a/c clutch. Try using those information to narrow things down. There isn't much electrical components other than the thermal switch on the compressor and the temperature probe on the evaporator. I have had that evap probe show open circuit and was reading at a freezing temperature and it won't cycle on the compressor. There's no live data so you will have to check the resistance it will be in the kiloohms there should a spec on shop manual.

[@vincentgonzalez307]

@@theoffroadingmechanic I don't have a live data Scanner, I did the diagnostic function and there is no codes flashing, I did checked for continuity on Thermal protector and it good, I will check the resistance on the temperature probe. Thank you.

[@d46512]

@@vincentgonzalez307 You could just have a leak. System needs a minimum pressure to operate.

[@NamNguyen-ir6er]

So you should check clearing gap AC COMPRESSOR GAP ???

[@ruslinyatim8508]

Hi i m from malaysia. Luckily i am find this video. My dad 91 accord cb7 got simptom very similar like this. Here ambiaent temperature always hot more than 30°celcius. I hook up the manifold gauge and see Low side pressure reading around 40psi meanwhile high side pressure is 100psi. Static pressure around 90psi. That mean refrigerant enough at all. Air from vent not cool at all, just warm. When compresor disengage both pressure reading rapidly going equalis. Last month just replace new ac compressor, new condenser and cooling coil, and filter drier too. This thing happened suddenly before yesterday where before the ac system just fine. Does this indicate that the expansion valve stuck open..

[@theoffroadingmechanic]

What is the compressor doing when it engages. Does it short cycle. Or when the compressor kicks off the low side increases really quickly? And an older vehicle are your blend doors working?

[@ruslinyatim8508]

When ac on,compressor always on,no cut off.. I just off ac by myself then see both reading pressure increase really quickly..

[@theoffroadingmechanic]

I haven't worked on many 91 accords with a/c issues but I'm pretty sure it's just behind the glove box for the evap core and expansion valve. The temperature bulb/probe I believe is part of the expansion valve. You might just have an expansion valve that's stuck open not creating a restriction to create that cooling effect.

[@ruslinyatim8508]

@@theoffroadingmechanic just now today i already take out the evaporator and expansion valve as well. Tomorrow i'll buy expansion valve and replace it. Hopefully after replace it the ac system will back to normal. Thanks brother for reply and advice.

[@ryanmccabe8712]

Hi, did the expansion valve fix your problem? I am having the same issue with a bus. It has two expansion valves and I'm getting the same reading as you.

[@mrdj-qb7os]

Brother i got problem in my honda civic. 40psi lowside 200 highside on idle Rev 2000rpm 30lowside 200highside. Maybe the expansion valve problem or compressor?

[@theoffroadingmechanic]

What are the symptoms other than pressure? is your condenser fan working?

[@mrdj-qb7os]

@@theoffroadingmechanic not cold on idle. Only cold when its running or reving. Yes fans are working high speed

[@theoffroadingmechanic]

Does the compressor short cycle? Kicks on and kicks off?

[@mrdj-qb7os]

@@theoffroadingmechanic compressor turning all the time

[@theoffroadingmechanic]

Pressure seems ok it's what it is doing at idle. Do you have the correct amount of charge? Is the air gap on the compressor clutch within spec?

[@SPMech1]

👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍

[@christiangerber7243]

Why does the pressure gauge on the low side call you a retard if the pressure is too high? 😢

[@Toxo]

Nonono, that's just a retarded amount of pressure! It's calling the pressure retard, not you! You are a beautiful and intelligent mechanic human being!

[@theoffroadingmechanic]

It says the same thing on all 3 of our machines. Maybe the pressure isn't suppose to go that high.

[@Ra_i_der]

I don't know much about cars. Where my expansion valve is located I feel air coming out is that normal or it's a bad expansion valve???

[@d46512]

A small air leak from blower motor inside the cabin could be normal. Is there a leak of freon?

[@maniksinghsalaria3892]

My suzuki swift blows normal air for 3-4 seconds then cool again and again after 5-6 minutes normal air blows for 3-4 second then cool again while driving ? What is possible cause

[@cloudypac]

Gas

[@ImGerald]

Mines stuck open on my van. Is there a way to clean and unstick it?