A/C blowing cool problem: Diagnosis Confirmation

[rgorke]

After reading multiple threads, I want to try and confirm my diagnosis. Several months ago, I noticed the passenger side center dash vent blowing warmer air or more correctly, air that isn't as cold as the driver's side.

A few days ago, the both sides are blowing only cool air, not cold. I ran the DATC self test and got no codes. This morning when I started the car, the AC blew nice and cold until it started to warm up, then only cool air.

So, I am fairly certain the issue is with the DCCV. Am I correct? Is there anything else to check? And yes, I know to put in a Motorcraft when I replace it!

Thanks!

 

[joegr]

It could be the DCCV. The symptoms also fit with low refrigerant level. Do you get any hissing sort of noises now and then from the center of the dash?

 

[rgorke]

It could be the DCCV. The symptoms also fit with low refrigerant level. Do you get any hissing sort of noises now and then from the center of the dash?

Yes!!! It will hiss like a valve is opening and closing.

 

[SultanGris]

I have the occasional hiss also, and my dccv is new. Don't think my cooling fan is working correctly so I've been using heat instead of the AC mostly but when I do use the ac it works great till my car starts overheating and I gotta switch back to heat to cool it off, ha

 

[joegr]

Yes!!! It will hiss like a valve is opening and closing.

That's the expansion valve trying to compensate for low refrigerant.
Don't use one of those DIY refill cans with the single gauge. Not only can't you get the level just right, but they always throw in more stuff like leak stop and whatever. Everything that is not refrigerant just reduces cooling capacity. The leak stop can cause the expansion valve to stick, and that requires the whole dash to come out to fix.

 

[joegr]

I have the occasional hiss also, and my dccv is new. Don't think my cooling fan is working correctly so I've been using heat instead of the AC mostly but when I do use the ac it works great till my car starts overheating and I gotta switch back to heat to cool it off, ha

You really should fix your cooling system. You have the electric fan, so it is easy to diagnose. Pretty much it either works completely, or doesn't work at all. Problems with the plastic cooling system parts, and with aftermarket replacement parts are far more common than electric fan problems. I don't recall where you are with your cooling system.

 

[SultanGris]

You really should fix your cooling system. You have the electric fan, so it is easy to diagnose. Pretty much it either works completely, or doesn't work at all. Problems with the plastic cooling system parts, and with aftermarket replacement parts are far more common than electric fan problems. I don't recall where you are with your cooling system.

I've replaced nearly everything but the fan, my thermostat might not be motorcraft but everything else is. Just got new motorcraft aux pump cause my new aftermarket one keeps blowing the fuse. Fan spins but I don't think it goes full speed, can't hear it full speed like you can on other cars. My overheat issues are intermittent but I'm running with no aux pump at the moment, gonna swap soon but was thinking of replacing fan at same time

 

[joegr]

I am going to bet on the aftermarket thermostat instead of the fan. This is experience based.

 

[rgorke]

That's the expansion valve trying to compensate for low refrigerant.
Don't use one of those DIY refill cans with the single gauge. Not only can't you get the level just right, but they always throw in more stuff like leak stop and whatever. Everything that is not refrigerant just reduces cooling capacity. The leak stop can cause the expansion valve to stick, and that requires the whole dash to come out to fix.

So, unless I have all the correct equipment, I need to take it somewhere for recharging. Or are there DIY options that don't use the single gauge?

 

[SultanGris]

I am going to bet on the aftermarket thermostat instead of the fan. This is experience based.

I was thinking that at first also, but I still need to follow your fan trouble shooting steps you gave me in the other thread and see what happens. I'm nearly certain it never runs as fast as it should. I have an extra thermostat that was in my broke plastic housing, I think it's motorcraft, I was gonna try that one if I can't get fan running faster.

 

[joegr]

I was thinking that at first also, but I still need to follow your fan trouble shooting steps you gave me in the other thread and see what happens. I'm nearly certain it never runs as fast as it should. I have an extra thermostat that was in my broke plastic housing, I think it's motorcraft, I was gonna try that one if I can't get fan running faster.

You need the Motorcraft thermostat housing / crossover tube assembly as well. The aftermarket one restricts coolant flow.

So, unless I have all the correct equipment, I need to take it somewhere for recharging. Or are there DIY options that don't use the single gauge?

Well, you can get a dual gauge set and can fill valve, if you know what you are doing.

 

[04_Sport_LS]

I've replaced nearly everything but the fan, my thermostat might not be motorcraft but everything else is. Just got new motorcraft aux pump cause my new aftermarket one keeps blowing the fuse. Fan spins but I don't think it goes full speed, can't hear it full speed like you can on other cars. My overheat issues are intermittent but I'm running with no aux pump at the moment, gonna swap soon but was thinking of replacing fan at same time

If your LS is overheating, the fan would sound like a jet engine if the engine temp is being read properly.

You say the overheat is intermittent. That sounds like you have air in the cooling system... which can affect cooling fan function.

 

[SultanGris]

If your LS is overheating, the fan would sound like a jet engine if the engine temp is being read properly.

You say the overheat is intermittent. That sounds like you have air in the cooling system... which can affect cooling fan function.

Yeah that's what I mean, I never hear the jet engine so I suspect the fan more than the thermostat at this point.

I've bled it multiple times, no air came out after the first time, water level and pressure stay good now. Of course I'll have to do it again when I replace the aux pump but I have good heat and I'm confident there's no air in the system. I replaced my coolant system one part at a time so I've gotten pretty good at it, ha

 

[rgorke]

Well, you can get a dual gauge set and can fill valve, if you know what you are doing.

I took it to a buddy who topped off the refrigerant. Now blows nice and cold!

Thanks! Much better than buying and installing a new DCCV (even though its not too big a job).

 

[SultanGris]

Fan update, runs full speed if you plug scanner in and tell it too, but it runs slower than computer demands, and fluctuates from demand and actual speed somewhat randomly. I gotta find that other thread again and hotwire it like you told me until I can get a new one, gonna be 90 this week! Thanks.

 

[joegr]

... I gotta find that other thread again and hotwire it like you told me until I can get a new one, gonna be 90 this week! Thanks.

Cut the White/black wire going to the fan and it will run full speed the whole time the ignition is on.

You will be treating the symptom instead of the problem. The result is that you will wear your fan and your alternator out pretty quickly, while the coolant flow problem remains.

Your test shows (as very likely) that the fan is okay, the wiring to it is okay, and the PCM fan control is okay.

 

[SultanGris]

Cut the White/black wire going to the fan and it will run full speed the whole time the ignition is on.

You will be treating the symptom instead of the problem. The result is that you will wear your fan and your alternator out pretty quickly, while the coolant flow problem remains.

Your test shows (as very likely) that the fan is okay, the wiring to it is okay, and the PCM fan control is okay.

Thanks. So you're saying the coolant flow through the aftermarket thermostat is the issue? I don't understand why it won't ever run fast when it's hot in that case. I've seen 215 and it never runs over half speed according to the diagnostic computer. I was gonna buy a new fan but it's gonna be 90 degrees for 3-5 days until it arrives is why I wanted to do that temporary solution.

 

[joegr]

215 is still in the low fan speed area. Highest fan speed doesn't come till it's over 236 at the CHT sensor. There is also a coolant return temperature sensor (of sorts), and it will read low when the flow is not good. Cool coolant coming from the radiator, means that higher fan speed is not needed.

It gets pretty hot here in the summer (we really only get two seasons here, summer and fall), and even so the fan can keep the idling engine cool at a very low speed. However, with the AC on (and the system charged and working correctly), the high side AC pressure triggers the fan to run pretty strong.

 

[SultanGris]

215 is still in the low fan speed area. Highest fan speed doesn't come till it's over 236 at the CHT sensor. There is also a coolant return temperature sensor (of sorts), and it will read low when the flow is not good. Cool coolant coming from the radiator, means that higher fan speed is not needed.

It gets pretty hot here in the summer (we really only get two seasons here, summer and fall), and even so the fan can keep the idling engine cool at a very low speed. However, with the AC on (and the system charged and working correctly), the high side AC pressure triggers the fan to run pretty strong.

Ok, I'll try the thermostat first then, but when when I run the ac it doesn't go full speed either so something has to be wrong with it.

 

[joegr]

Ok, I'll try the thermostat first then, but when when I run the ac it doesn't go full speed either so something has to be wrong with it.

Yes. The AC shouldn't normally bring it up to full speed, but it should bring it high enough to notice for sure. It's probably low refrigerant, but it could be a problem with the scroll control valve or the expansion valve. To determine which it is, you need high and low pressure gauges. You should check the underside of the compressor to see if it is wet with oil. If it is, then you probably have the all to common scroll control valve o-ring leak. If you do and you refill without adding compressor oil, it will kill itself and you will have to replace the compressor, condenser, and dryer.

 

[SultanGris]

Yes. The AC shouldn't normally bring it up to full speed, but it should bring it high enough to notice for sure. It's probably low refrigerant, but it could be a problem with the scroll control valve or the expansion valve. To determine which it is, you need high and low pressure gauges. You should check the underside of the compressor to see if it is wet with oil. If it is, then you probably have the all to common scroll control valve o-ring leak. If you do and you refill without adding compressor oil, it will kill itself and you will have to replace the compressor, condenser, and dryer.

Okay thanks, I do have that occasional hiss in the dash on startup so it probably is low, I'll check that first then. Thank you very much sir!

 

[joegr]

Also, remember it is not just the thermostat itself, it is also the housing that is the problem.

 

[AmsterDutch]

It's probably low refrigerant, but it could be a problem with the scroll control valve or the expansion valve.

I do have that occasional hiss in the dash on startup

Joegr just gave you the answer and you confirmed it...
Also like 04' Sport said ...make sure to get those air pockets out and bleed it properly after you replace the T-Stat

 

[SultanGris]

Well I'd have never believed this is I didn't see it myself but my fan started working after I replaced aux pump with a motorcraft one and added coolant, previously was just pure water. I knew they ran a little warmer on pure water but I thought the fan would still work when the temperature got hot. Very interesting.
EDIT: nevermind, it quit working again already.

in other news my refrigerant was good but he said it wasn't pumping good enough so he thinks my compressor is weak, he wants to suck it all out and put it all back in with oil but he didn't have time to try that today.

 

[SultanGris]

Works good now, thanks! Need to run a toggle switch inside them I'm golden, ha!