88 New Yorker HVAC issues

[1986GLH]

So since I swapped a 2.4 in my 88 New Yorker Turbo, I have been having issues with my heating/air conditioning. Before the AC was charged, I would have the heater control all the way to cool and it would still blow in some heat. Now with the AC charged, the AC works great until the engine is warmed up and then it no longer blows cold. During the 2.4 swap, I got rid of the heater control valve under the hood. Could this be the reason why? Or is the issue in the HVAC assembly?

[83scamp]

With the heater control valve gone, you will always have hot water running through the core. So a little bleed by is to be expected. But, it shouldn't be enough to significantly impact the A/C working. I got rid of the bypass valve in my Daytona, and the A/C still blows ice cold, even on a 134a converted system. My bet is either the temp door isn't closing all the way, or the foam seals for that door are toast. The more likely answer is the seals are toast. After 20+ years, the foam they used at the factory pretty much turns to dust.

Unfortunately, the only real solution, is to pull the HVAC unit, and rebuild it. I used the black foam pre-filter for a window A/C unit as replacement seals in mine. You can usually get it at your local hardware store for a couple bucks for a 16X24 sheet. One sheet will do most HVAC systems.

[1986GLH]

With the heater control valve gone, you will always have hot water running through the core. So a little bleed by is to be expected. But, it shouldn't be enough to significantly impact the A/C working. I got rid of the bypass valve in my Daytona, and the A/C still blows ice cold, even on a 134a converted system. My bet is either the temp door isn't closing all the way, or the foam seals for that door are toast. The more likely answer is the seals are toast. After 20+ years, the foam they used at the factory pretty much turns to dust.

Unfortunately, the only real solution, is to pull the HVAC unit, and rebuild it. I used the black foam pre-filter for a window A/C unit as replacement seals in mine. You can usually get it at your local hardware store for a couple bucks for a 16X24 sheet. One sheet will do most HVAC systems.

So looking inside the HVAC system, the foam looks to be in really good condition yet. I'm starting to wondering if the temp control lever isn't fully closing the blend door. So I'm going to look at that today.

[Dr. Johny Dodge]

you're getting hot air because you deleted the water valve - no other reason
without the valve you will always have hot water flowing through the heater core
this is how you get heat in the car to start with
the a/c core shares the same space in the box with the heater core thus the two will compete to affect interior temp unless one is not working
thus you must have the water valve to stop the hot water from reaching the heater core when you want the a/c to function properly

without the water valve the heater core is always going to run at full engine temp
if the water valve wasn't needed for proper function mopar would never have installed it in the first place

[83scamp]

Hate to disagree, but on K-based cars, the heater core & and evaporator do not share the same space. They are on opposite ends of the heater box. There is a wedge shaped temp door that controls how much air goes over the heater core on the driver's side of the heater box. The evaporator is on the passenger side, right next to the fan, and the heater core is on the driver's side. The heater door is controlled by a cable from the temp lever. It can get out of adjustment and not allow it to close properly.

Like I said above, I eliminated my bypass valve two years ago, and even in the heat of summer, I have ice cold A/C. A properly adjusted & functioning HVAC unit seals the heater core off, so very little gets by and affects the A/C function.

Another thing to check is how well the vacuum system that operates the other doors is working. If you have a leak in the vacuum lines, it can cause the doors to move under low vacuum/boost conditions and that can allow some heat through as well. The one way check valve coming from the brake booster is a known failure point. It is designed to let the system see vacuum but not boost.

[4 l-bodies]

The factory eliminated the bypass valve on later years. I also have eliminated the valve several times with no noticeable AC cooling issues. The aftermarket valves are terrible, they leak all the time anyway. Justin I would agree with 83 scamp, if your foam is in good shape, make sure cable is adjusted properly and check valves are still functioning properly. If you disconnect the cable, and operate it by hand, you should be able to clearly hear the door shutting against its stop. If you are experiencing changing vent output positions while driving vehicle, you have check valve issues. Pretty common problem on vehicles running larger than stock boost levels. I had all kinds of HVAC issues when I first bought my yellow Shadow.
Todd

[1986GLH]

The factory eliminated the bypass valve on later years. I also have eliminated the valve several times with no noticeable AC cooling issues. The aftermarket valves are terrible, they leak all the time anyway. Justin I would agree with 83 scamp, if your foam is in good shape, make sure cable is adjusted properly and check valves are still functioning properly. If you disconnect the cable, and operate it by hand, you should be able to clearly hear the door shutting against its stop. If you are experiencing changing vent output positions while driving vehicle, you have check valve issues. Pretty common problem on vehicles running larger than stock boost levels. I had all kinds of HVAC issues when I first bought my yellow Shadow.
Todd

Hey Todd,

I'll double check the blend door again tomorrow, but it seemed to be fully closing. I know I have popped vac hoses off in the past so had to replace the check valve. I'm not having the changing of vents issue, so don't think it's vacuum related. So, it almost has to be the blend door.

[1986GLH]

So Todd, you were correct. The blend door wasn't fully closing, so I adjusted it and am no longer getting hot air.

Now though, it seems the pressure switch is having issues. The compressor will cycle on when I jump the two clots in the connector together. It will also cycle on if the car has been sitting for a little while, but not very long. Do I need to evacuate the freon to replace the pressure sensor or is their a schrader valve in there?

[83scamp]

Have you put gauges on it to check pressures when running? My guess is, you may be a little low on freon. Is it still R12, or have you converted to R134a? Earlier this year, mine would run, but not cool as well as I hoped. When I put my gauges on it, the pressures showed it was a little low. Added another can of 134a, and it will about freeze you out now...

[4 l-bodies]

Justin,
83scamp called it too. My Shadow had a schrader valve on pressure switch, but can't say for certain if yours does or not. I'm guessing it probably does. I also would guess it may be a little low on Freon. I certainly would try that first. If you need a cheap r134a gauge, I have one you can use.
Todd

[1986GLH]

The car has been converted to r134a. It also is using an AC compressor from a 2003 Stratus. So I hooked my r134a gauge to it and the pressure is 70-80 with the car off. When I start the car and turn the AC on, the pressure goes to 0. I hope the freon isn't low since I just had the system charged 2 weeks ago after I finished my AC lines. So would it need more freon or could it be the expansion valve is plugged? Also, just wanted to say thank you for all of your help.

[wheming]

The car has been converted to r134a. It also is using an AC compressor from a 2003 Stratus. So I hooked my r134a gauge to it and the pressure is 70-80 with the car off. When I start the car and turn the AC on, the pressure goes to 0. I hope the freon isn't low since I just had the system charged 2 weeks ago after I finished my AC lines. So would it need more freon or could it be the expansion valve is plugged? Also, just wanted to say thank you for all of your help.

Sounds like you have a leak somewhere.

[black86glhs]

The car has been converted to r134a. It also is using an AC compressor from a 2003 Stratus. So I hooked my r134a gauge to it and the pressure is 70-80 with the car off. When I start the car and turn the AC on, the pressure goes to 0. I hope the freon isn't low since I just had the system charged 2 weeks ago after I finished my AC lines. So would it need more freon or could it be the expansion valve is plugged? Also, just wanted to say thank you for all of your help.

If the pressure goes to 0 and the compressor cycles a lot, you have a leak.

[1986GLH]

If the pressure goes to 0 and the compressor cycles a lot, you have a leak.

The pressure goes to 0 and the compressor stops cycling. Then I turn the car off and wait 15 minutes and the pressure is back up to 80psi.

[wheming]

The pressure goes to 0 and the compressor stops cycling. Then I turn the car off and wait 15 minutes and the pressure is back up to 80psi.

What you described is entirely normal if you have leaked out most of your charge.
Look over all your lines and connections and you might see a dirty/oily spot (if you are lucky). If the leak is in the evaporator, you won't see it and will have to be found with a refrigerant detector.

[EaZyE426]

The low side will go to 0 when the compressor charges the high side. Once it sits, the high pressure leaks back to the low side and that's where you see the 80psi again.

[black86glhs]

The low side will go to 0 when the compressor charges the high side. Once it sits, the high pressure leaks back to the low side and that's where you see the 80psi again.

It doesn't leak back, but rather the pressures equalize since the compressor is not running. Not trying to be a d*ck about it, just rather see the appropriate terminology.

[EaZyE426]

I could throw out big words all day long, but in the end, using laymen's terms gets the point across better.

[1986GLH]

So I took the New Yorker to my brother to sort out the a.c. it turns out that the drier had brown milky stuff coming out of it. So replaced both that and the expansion valve and the a.c. works great now. When he evacuated the system, he pulled out the same amount that he charged it with a couple of weeks ago. It's good to know it wasn't leaking. I guess I should have replaced the drier when I did the lines since they were exposed to the elements for almost 3 years.

[wheming]

So I took the New Yorker to my brother to sort out the a.c. it turns out that the drier had brown milky stuff coming out of it. So replaced both that and the expansion valve and the a.c. works great now. When he evacuated the system, he pulled out the same amount that he charged it with a couple of weeks ago. It's good to know it wasn't leaking. I guess I should have replaced the drier when I did the lines since they were exposed to the elements for almost 3 years.

Ah, yes.
Anytime you open the system and replace lines or components, best practice is to replace the drier.
Based on your new details, the expansion valve was probably plugged with debris, causing the compressor to pump down not getting and vapor back through the suction (and why pressure would go to zero and cycle off).

Glad you are back in business!