looking for trouble shooting help
symptom :
warm air at vent, same as outside temp
testing:
I evacuated the system and it held 30 in/Hg vac for 20 mins, recharged with about 16 oz R134A (spec approx 14.6 oz)
with a gauge set, the pressures bounce a bit, according to when the radiator/condenser fan is on....with fan on, low about 25 psi, high about 190....after the fan stops, they get up to 40 and 250 then fan comes in and they go down.... ambient temperature 70-75F...spec low 30-40, hi 190-220
functioning:
compressor runs/clutch engages non stop with AC ON, condenser fan cycles on low speed with AC on....I believe theses are working as designed. If I turn the system off and turn the car off the pressures are at 90 on low side and 120 on high side after about 8 minutes.
note:
I could hear refrigerant moving through the evap coil under the dash. Cabin air filter under the passenger side dash was filthy and has been removed waiting for a new one-cover is closed where it is accessed.
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Previous owner indicated entire system rebuilt about 14k miles and 32 months ago, The compressor and condenser are new looking. The accumulator is part of the condenser assembly, these appear to be newish.
Recently replaced radiator fan low speed resistor.
Tonight I plan to access evap coil and see if outbound tube is cool to touch...although, there's no water puddle under the car when parked for several minutes with AC ON...no condensation means no cold evap core...?

 

I got back back into troubleshooting last night. First thing ii did was thoroughly clean both sides of the condenser. Currently, there's not acabin air filter in place.
​​​​​​ I once again evacuated the system, watched it maintain 30 in/hg vacuum for 30 mins after I turned the pump off. Then refilled it with 12 oz of r134a. Are the pressure levels are appropriate for the outside air temp of 70 F? 25-35, and 170- 250. At the condenser, there's a major temp difference between the two lines going in and out.
Both lines between the expansion valve and the evaporator are cool to the touch. I observed the blend door arm moving appropriately as I turned the temp on the control unit up, and the air at the vents got hot.
With AC ON I'm still getting no cooling at the vents
.

 

I noticed this hose at the compressor which appears to be leaking. But not preventing the system from holding vac or maintaining normal gas levels. I recently resolved oil leaks from pan gasket and CPS o ring...over a month ago

 

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Sounds like the system should be working. My first instinct says the expansion valve just isn't working properly as that would be one of the more common failure points.

Could be an issue internally with the evaporator (partially clogged), but that is rare. Perhaps a mouse nest in the evaporator housing? Or an internal blend door malfunction?

If you have more time than money I'd try to visually inspect the evaporator core. If you have more money than time, replace the expansion valve.

 

Sounds good, thanks for the input. I spoke with the mechanic who did the rebuild 32months ago. He was not suspect of the expansion valve. He suggested trying to confirm the cool low side tube on the engine side of the firewall, and to add a little more r134a...I have 12oz now. He also said to use soapy water and see if there's a significant leak at that compressor hose
any tips on accessing the evaporator core?

 

I've seen plenty of expansion valve failures, new and used, I don't know why your mechanic would discount that part as a potential trouble source. With your pressures and description of how your system is working you should be getting at least some cooling.

The expansion valve is a spray nozzle, not unlike that of a spray can. Have you ever used a spray can that spits and sputters but still works? You are still changing pressures, high side in the can, low side out of the nozzle, but your paint surface (cooling) sucks. A malfunctioning expansion valve can cause poor cooling, yet not completely disrupt your pressures. It's not a common problem, but I have seen it happen.

I have seen plenty of externally restricted evaporator cores, mouse nests, leaves, dust accumulation, or blend door problems. But I have not seen many internally clogged evaporator cores, usually the result of desiccant bag failure, sometimes compressor failure. If an evaporator fails it's usually a leak. Sorry, I can't help you with visually inspecting your evaporator, but it's usually a big job.

 

the previous owner's mechanic could be trying to save face by saying the TXV is good....who knows.....he's about 2 hours from me.
your description makes sense of the spray nozzle. Someone else suggested just trying to clean this one.
I was getting some cooling, on an 85 degree day, only a drop of 5 to 10 deg ....this morning I had an ambient temp of 67F and a vent temp of 60 F...
I hate throwing parts at a car, hoping it's the fix.....but sometimes it has to be done. rolling the dice, I'll plan to swap the TVX and put in a new cabin air filter this weekend
thanks again for the input!

 

swapped the txv today and put in a new cabin air filter yesterday... I was expecting a real nightmare of a job for the expansion valve, but it was pretty straight forward- I had to stop and go get a T25 screwdriver.... evacuated for 90 minutes, held vacuum for 30 min then recharged with approximately 13.5 oz of r134a and added 1 oz of PAG... a good bit blew out when out when I evacuated the system. F
I finished just before dark with an ambient temp of about 77F....I was getting much cooler air, but still only about a 15-20 degree drop at the vents (58-64F)....pressures were low 25-35 ish, high 175 to 240ish.....upon shut down both sides balanced out in about 5 minutes....
maybe there's some air leaks around the duct work under the dash?
2004 170k miles

 

Well, that's an improvement. What did the passages inside the old expansion valve look like?

Ambient temp isn't very high. Try the system under normal operating conditions but higher ambient temperatures.

Possibly could add a tick more refrigerant.

What is the air velocity like from the vents?

My gut feeling is that there was a compressor or desiccant failure in this system and you are fighting some contamination issues.

 

I'll post pics of the old txv....air flow at the dash vents are very very strong....which points to? no evap blockage and tight duct work???. The prior owner did and ac rebuild kit about 32 months and 16k miles ago....professionally installed

 

no gross evidence of abnormalities, to my novice eye


also worthy of mentioning, I've yet to see a puddle of water on the ground after running the AC....nor have I noticed a wet floor in the cabin

 

Drove about 40 miles this morning then hooked up the gauges to check again. Ambient temperature 77F with high humidity (60-80%)
First thing I noticed pressures are gloriously normal....30-40 and 170 -220...here's a posting from NAM

 

Second thing I noticed is a massive difference between centerdash vent and glove compartment vent, over 25 degrees cooler in the glove box, center dash is warmer than ambient temperature. Passenger side dash vents warmer than glove box, driver side vents warmer than passenger side vents.

 

Here's what I put in for refridgerant, 12 oz can and 3 oz can... Includes 1oz oil and 1 oz cold enhancer. If

I need more, it would only be an ounce or so.

 

from the glove box I can see the part #2 " temp control actuator" linkage working to move the heater core blend door, as I turn the desired temp up or down.
Also, with the cabin filter removed I can see the actuator going between fresh or recirc air
Part #3, air dist actuator is easily accessed with the stereo HU and climate control module moved out of the way, this is a Bosch servo/actuator to choose floor, panel or defrost
Since all these are working, I guess I have to confirm the blend door is closing 100% with max AC, and I have to look at and confirm all the duct work and unions are tight.

....maybe I need parts #2 and/or 3...air distribution actuator, temperature control actuator

 

Yeah, right from the beginning your pressures seemed in the range of normal. Expansion valve looks okay, but often times they do look okay but aren't functioning properly.

Still could be a blend door problem. If the blend door isn't working and sealing properly that can affect the air conditioning. In most cars the blend door separates the heater core (hot) from the evaporator core (cold). Think of a faucet in your house. If your hot water side of your tap isn't sealing completely, your cold water will never get completely cold. I've seen many blend door problems, bad seals, debris, stripped actuating arms, mouse nests, etc. I will say I am not familiar with your specific housing design, but most work off of the same basics. Unfortunately it's a big job to take it apart to inspect it so I'd hate to recommend that repair route and have you find nothing.

 

I've changed blend door actuators before, not fun, but better than cooking in summer time. I'm going to start pulling the dash and center console apart. All of the actuators are available new and not terribly expensive. I DIY tech article/write up would be helpful

 

here's the cold, and heated, air ducts....maybe there's some gaps around these AC ducts

 

I'm curious. I'll be following along. Thanks

 

removed a bunch of trim, center console pillars and shifter surround, radio hu, climate control and accessory switch panel, glove box, dash top cover. easily visualized and no problem confirming all 3 actuators work.
baffling
I'm definitely getting cold air at the small duct from the evaporator to the glove box. Next I'll have to check for tight fittings from the air handler to the dashboard output vents...fun fun fun

 

Condensation has to be going somewhere. Have you checked for a stopped-up drain?

 

It was tinkling a small puddle on the asphalt last night....the top dash center vent was 30 degrees warmer than the glove box.
Tonight I might remove the blend door actuator/ servo and manually confirm it's closing completely. The small parts linkage just to the left of the glove box all appears to move to both extremes, suggesting fully opened and closed.

 

found this picture of my hvac unit, Valeo W964407P.... maybe I just need to re-do the weather stripping on the top unions, the big rectangular one in the middle feed the dash vents. ...the fresh/recirc air supply is to the far right, distribution controller is on bottom left; blend door actuator is in the middle-ish next to where the cabin filter goes.