AC system working but no cold air in cabin

[Kite]

I have searched around and cannot find a thread that addresses my specific issue with my new-to-me 2003 100LC. The climate controls and AC worked great for the first 2,000 miles or so (that I have owned it) but now I am having issues.

I do not have cold air in the cabin. I have confirmed that the AC system is working- the compressor/pump cycles on and off when switched in the cabin and the lines get hot and cold. All of the air vents work and fan speed settings work. Heat also does not work unless it is set to "max hot." There is no gradient in temperature whatsoever- anything other then "max hot" blows ambient outdoor air as if the AC and Heat were shut off.

It seems to me that this could be blend door issue or something along those lines?

Thanks for the comments and advice and FYI, it'll be next week before I am able to work on it some more.

 

[phatdragon]

Have you checked the refrigerant level?

These work pretty well.

 

[diego355]

Take it to a shop for them to perform a leak and vacuum test, after that if it passes recharge with R134a.
Make sure that they also oil the compressor and inject fluorescent dye to inspect for further leaks.
The can mentioned abobe works but it will not identify leaks, just a temporary fix. It will leak out again.

 

[Kite]

I will do some checks, but I am 99% sure that it is not an AC system issue because of how the compressor is operating and how cold/hot the lines are combined with the fact that there is no heat unless set to "max hot." What do these vehicles have for a blend door mechanism?

 

[flintknapper]

I will do some checks, but I am 99% sure that it is not an AC system issue because of how the compressor is operating and how cold/hot the lines are combined with the fact that there is no heat unless set to "max hot." What do these vehicles have for a blend door mechanism?

^^^^^

Agree with your assessment.

I am not familiar with the under-dash workings or plenums and blend doors/sensors...so I can offer no help there, but I think you are on the right track considering the symptoms.

 

[1972FJ55]

If the lines are cold & hot going into the firewall, it's most likely a blend door actuator.

 

[2001LC]

See if AC works on max cold. If so look to see if cabin hose and sensor are connected just below IG key. You'll see 1" squar vent below IG key. Behind is where these reside.

 

[Kite]

Max cold AC has not worked, but I was going to check that sensor out as well. Thanks for the photos 2001LC!

 

[2001LC]

Have you hook-up a manifold to AC "H" & "L" and check pressures?

When you say compressor/pump cycles on and off. Are you seeing magnetic clutch engage?

If you pull glove box, can see door (servo) for fresh air open and close?

You should also be able to feel fresh air coming from vents at HWY speeds, if set to outside air. If heat turned to hot, it should feel warmer than outside air temp (OAT). If control set to cold, it should feel as cool as OAT. AC off, fan on to set then off to feel air free flow through vents.

Clues!

 

[Dwight S]

Possibly the expansion valve on the lines at the evaporator. Mine would cool for a few minutes then go warm. Turn it off, let it sit then turn it, same result. Replaced the expansion valve and it works as it should.

 

[nukegoat]

Possibly the expansion valve on the lines at the evaporator. Mine would cool for a few minutes then go warm. Turn it off, let it sit then turn it, same result. Replaced the expansion valve and it works as it should.

This

 

[flintknapper]

Possibly the expansion valve on the lines at the evaporator. Mine would cool for a few minutes then go warm. Turn it off, let it sit then turn it, same result. Replaced the expansion valve and it works as it should.

^^^^

Classic symptoms of your TXV freezing up (moisture in system). Evacuating the system, pulling a good vacuum, new drier and recharge alone would probably have solved your problem. TXV's do go bad (stick open, closed or somewhere in between) but doesn't sound the OP's problem.

 

[Kite]

Upon further investigation, I do not think that the blend door is the issue and I am fairly certain that there is a heat gradient when operating the heater.

I think I am going to try the DIY recharge kit. It is cheap and easy to do so might as well try the first.

 

[flintknapper]

Vent thermometer is your friend.

Amazon product

 

[Dwight S]

If the expansion valve has failed, no amount of refrigerant will make the system work better and overfilling it could ruin the compressor.

I recommend biting the bullet and have a professional diagnose it or buy a set of gauges and learn how to hook them up and read them.

 

[flintknapper]

Upon further investigation, I do not think that the blend door is the issue and I am fairly certain that there is a heat gradient when operating the heater.

I think I am going to try the DIY recharge kit. It is cheap and easy to do so might as well try the first.

^^^^^

Classic novice's mistake. The first thing they do is go buy DIY can of refrigerant and seek to 'pour in the cool'. Until you KNOW what your pressures are (evidenced by using a manifold gauge set) and have checked Superheat temps at the Evap, you risk doing damage to your system.

Did you check the hose and sensor connection as @2001LC suggested?
A simple vent temp thermostat will tell you if have heat gradients at the vent (though you can feel those by hand to a certain degree).
You said the compressor was 'cycling'...but if it is 'short cycling' (cycling every 20-30 seconds) then you have issues we need to check on.

The TXV controls the amount of liquid refrigerant that enters your Evaporator (thus maintains a constant Superheat). IF it is stuck open...it can flood the evaporator resulting in no cooling and possibly slugging your compressor. IF it is stuck shut, then again no cooling but it will be obvious by the pressure readings. IF stuck in the middle....poor cooling performance, evap will likely freeze up, but this usually manifests as cooling for period of time, then none...until the unit is shut off and the evap thaws out.

But I wouldn't be too quick to blame the TXV without first doing some testing...which will require equipment you probably don't have.

Low refrigerant charge: Is a possibility....but from your initial post it doesn't sound as if you are getting any cool air from the vents? That just doesn't jive with compressor cycling and fan speed air from the vents.

Highly recommend you have a pro look at it....OR purchase a manifold gauge set and we can get some meaningful information that way.

 

[Kite]

Thanks for the responses. The compressor no longer cycles as it did in the beginning- it is just off the entire time. Also, the lines that were hot and cold, as stated in the original post, no longer change temperature. I have confirmed that there is a heat gradient when operating the heater. And correct, I am not getting any cool air from the vents and I wasn't even when the compressor was cycling (but without a thermometer, its a possibility it was cooling, just not enough to notice). My wife was driving it a bunch when this stuff was all going on and was out of town. Between work and being out of town, its been a piecemeal diagnosis. Thanks for the patience.

It seems to me it is either a low charge or the TXV.

P.S. My wife does love the LC despite having initial reservations about purchasing it.

 

[Davio6]

Hi Kite,
I agree, that you need to measure low and high side ac service port pressures. There are a variety of reasons for your problem. Some are mechanical, some are electronic. If I had to guess, and not all data fits, but a common scenario is a seller has a known ac leak, and recharges the system prior to sale, to make it look perfectly good. A month or week or some time later you go through the process of gradual ac shutdown.
The two items you address above are probably pro-level repairs, so I would at least have a shop evacuate, and leak check your system. That is where you will find either a leak or other malfunction including TXV.
Best of luck,
Dave

 

[flintknapper]

Hi Kite,
I agree, that you need to measure low and high side ac service port pressures. There are a variety of reasons for your problem. Some are mechanical, some are electronic. If I had too guess, and not all data fits, but a common scenario is a seller has a known ac leak, and recharges the system prior to sale, to make it look perfectly good. A month or week or some time later you go through the process of gradual ac shutdown.
The two items you address above are probably pro-level repairs, so I would at least have a shop evacuate, and leak check your system. That is where you will find either a leak or other malfunction including TXV.
Best of luck,
Dave

Correct and succinctly put.

 

[Kite]

Ordered some manifold gauges, vacuum pump, and what not and will get this thing properly diagnosed.