My 95 7.3 E350 air conditioning has issues, front air will work and blow cold then suddenly stop blowing cold and will blow hot - in awhile it might start blowing cold again, it just depends, no rhyme or reason that I have been able to see. Will work good then stopping going into the store and restarting and it will blow hot until it feels like blowing cold again, then at times it will go for extended periods without an issue.

Moving the function selector and temp control makes no difference.

Now, the whole time this is going on wit the front the rear air is working good and will always blow cold air.

Any help would be appreciatted.

Thanks in advance.

s.r.

 

Does the amount of air at the vents change, Steve? If it feels like the air flow is getting blocked, I would guess the front evaporator is icing up. Do you notice a lot of water under the van after is sits? That would be melt water.

It could also be an expansion valve on the evaporator, the rear unit evaporator has its own valve so it would work normally.

The only other thing would be a blend door that has come loose in the plenum. Can you detect any door moving when operating the temp control? The blend door sets the amount of from the evaporator and heater to adjust temperature. jim

https://www.ford-trucks.com/forums/1...a-c-issue.html

 

Thanks for your reply.

Only thing that changes is the temperature. I haven't been able to detect anything happening except for the temp change. The ice (or melted water) is nothing out of the ordinary.

 

When it changes temp, does it just go warm or does it feel like full blown heater air? If it just goes warm, the A/C, evaporator would be the problem. If it goes engine coolant temperature hot, that's probably a blend door.

If you can, the next time it switches, feel the tubes going into the evaporator, one will be scalding, flesh melting hot (don't touch that one), the other will probably be sweating and cool or cold.

 

it turns HOT!

 

Sounds like a blend door, then. Is it all automatic control or all manual? The auto systems have a temp readout and an electronic servo for blending the hot/cold air. If it is a manual control, probably a blend door problem.

 

manual actuation

 

Check the refrigerant charge. Requires a gauge set.


Post the low side AC system pressure at idle after engine has warmed up.


>>>>>>>>>Action

 

been recently charged, that was the first thing I did.

 

What is the low side reading when it blows hot?


>>>>>>>>>>Action

 

no idea, had recharge done by shop - issue existed before the service, when it was still acting up I took it back for recheck and while the van was there for recheck the air conditioning worked fine (aint that the way it always goes?) and they could see no issue.

 

If it blows cold air in back I would forget the A/C troubleshooting for now.

I do not know if your system uses electric or vacuum to operate the blend door. Here is a document on the electric system. You will have to determine which system you have. jim
https://dl.dropboxusercontent.com/u/...20ACTUATOR.PDF

 

In post 5 & 6 it was asked and you replied to a statement about the tunes going into the evaporator. The statement you amde was it turns hot. Meaning the AC system is not functioning correctly during the times of no cold air.

While some of the above items can and do cause that condition, if the evaporator isn't getting cold intermittantly that is a problem. Either because the system is low on referigerant or there is a restriction in the system usually from debris.

>>>>>>>>Action

 

I think it is electric, the temp control goes into box behind dash that is only wired in, that makes more sense than anything. will look at see if I can find the parts in the van. wish there were pictures. As fast as the temperature change is it is like the cold is shut off instantly and then started back the same way. Door or actuator most likely.

 

From the first post:That says A/C is fine. Even if the front evaporator were bad (failed expansion valve), it would not blow HOT. The heater and A/C both run all the time except on FLOOR on some models. The temperature control blends the 2 temps to get the desired temperature. If the controller for the blend door fails intermittently, the temp can change from full A/C to full HEAT instantly. Blend door and blend door actuators are common failures.
jim