Hi.
I have a ´89 F150 with 4.9l+M5OD and it has a A/C but it doesn´t work.
Any ideas where i should start looking?
Compressor clutch wont do anything when i turn A/C on,is that something what i should check first?


Tommi

 

Behind the dash and mounted above the a/c heater control panel is the: Air Conditioning Vacuum Selector Valve Assy. This is a multi-ported vacuum manifold that also has the a/c "kicker" switch on it. When you move the dash lever to A/C, the kicker switch "kicks on" the compressor. This valve also controls the blend door motors. When the lever is changed from one mode to another, the valve, operating by vacuum, opens one door and closes another. This function directs either warm or cold air to various locations: through the dash vents, to the defroster vents, or to the floor.


The valve is available from Ford. FTE sponsor DIRECTFORDPARTS shows the valve to be $18.67 list price, FTE member price: $10.55.

E1AZ-19B888-B .. A/C Vacuum Selector Valve Assy (Motorcraft YH-380)

 

Here's an easy test:
-Start the truck and turn on the AC.
- Locate the low side cycling switch. It's screwed onto a port on or near the Accumulator, 2 wire connector. Jumper the harness connector with a paper clip or piece of wire. The compressor should engage.
- If so, you are probably low on refrigerant. You just need to fix the leak and service the system.
- If not, there is an electrical problem. You'll need to get out the test lighr and start tracing the circuit.

 

Hi guys. Thanks for answers.
I´d like to test what would be the problem so i do that first before i order new parts. But its good to know that there is this "Air Conditioning Vacuum Selector Valve Assy" thingy that is one possibility.

lsrx101 wrote:
"Locate the low side cycling switch. It's screwed onto a port on or near the Accumulator, 2 wire connector. Jumper the harness connector with a paper clip or piece of wire. The compressor should engage."

Now i do need help. What is "low side cycling switch"? And what is "accumulator" also? Any pics or something?


Thanks,Tommi

 

The accumulator is the metal "can" mounted to the firewall on the right side. If you follow the fat hose on the compressor, the accumulator is on the other end.
The low side cycling switch is screwed to a port on the accumulator. It's a pressure sensing switch that cycles the compressor to maintain pressure in the evaporator.
- Accumulator- http://tinyurl.com/2gmac4
-Switch- http://tinyurl.com/2ff6df

 

I tried that paper clip method and it did engage.
What should i do next?


Tommi

 

OK, that means the refrigerant is low. Look closely at all of the AC lines, fittings, and the condenser (in front of the radiator). Oily dirt will usually show at the leak point. The oil leaks out with the refrigerant and collects dirt. If leaks are found at a fitting, the orings can be replaced. I would suggest replacing all of them. Look through the grille at the tube running down the left side of the condenser, the tube is prone to rust at the bottom where it enters the condenser.
Also look for oily dirt on the compressor clutch and the compressor body. If there is any sign of leakage around the compressor, you will need a new one.
Being an 89, this will be an R-12 system. If you can get R12, it's best to stay with that. You can also convert to R-134a with a little work. Lets find your leak first, then decide which way to go.

Do you have access to a vacuum pump and a manifold gauge set? You will need these if you want to service the refrigerant system. If not, you can do the repairs yourself and have a shop evacuate and recharge the system.

I just noticed you are in Finland. What refrigerants are available to you there. I know R12 and R134a have been banned in some parts of Europe but I don't know the particulars. How is parts availability for your truck?

 

I was told that its illegal to sell R-12 here in Finland also and they are selling R-134a nowadays.
Some guy also told that its possible to use Isceon 49 R-413A refrigerant and it wont need any modifications on my A/C system. Have you heard of this?

I´m still wondering why my magnetic clutch isn´t engaging when my engine is running. It´s just because i used to have ´86 Country Squire and it was low on refrigerant and it was engaging the clutch all the time,several times per minute but my truck wont do anything? Would it be possible that there´s electrical problem as NumberDummy suggested?


Tommi

 

R134a is the refrigerant preferred by the manufacturers of MVAC parts and the auto manufacturers. It is a "pure" refrigerant (There's a word for that but it escapes me at the moment) , where R-413 is a blend of Refrigerants 134a/218/and 600. With any blend, the system must be totally leak free because the "gas" that carries the oil will leak off first and starve the compressor. The only advantage to R-413a is that it is compatible with the existing mineral oil in the system. The main cooling component is the R-134a. You cannot "top off" a system running a blend if it does leak a bit. The fittings are (supposed to be) unique along with the equipment used to handle it. If I understand correctly, it costs more too.

The system is so low on refrigerant that the low side pressure switch isn't closing to engage the compressor. Your 86 had a little bit more static pressure in the system, that's all. The "paper clip" test proved out the electrical part of the system.

Your next step is to check for leaks. As I said earlier, look for oily residue on the lines, fittings and compressor. Start at the compressor and follow the lines to the condenser, to the evaporator and accumulator then back to the compressor. Also look for physical damage to the rubber hoses and corrosion on the metal lines. Let me know what you find.

 

Hi.

Today I checked every hose and fitting but I could not find any damp spots or anything.
I´ll go to A/C specialist and have it pressure tested and maybe that way I´ll find where it leaks.

Thanks again,i´ll get back on this when I have more information.


Tommi

 

Yes.. when the system is low, the compressor will cycle on and off, just like your other car.

When the system is VERY LOW (close to, or completely empty) the compressor will not come on at all.

 

Its a safety switch to keep you from KILLING your compressor when it is trying to run a system deviod of freon.

I have 3 1980's cars with original compressors. I do my own maintenance. All the units are quiet, and most important, COLD!!!

Bruce

 

I'm new at this kinda stuff so forgive me for not understanding. How do you "Jump" a switch? My A/C doesn't engage either and I would like to try this method.

Thanks!!!

 

ok so i just got the A/c on my truck recharged, i had it done by a professional, vacuum and leak tested and what not, every thing was good except it had no freon at all so i couldn't test the compressor, so we recharged it, and it blew somewhat cold, everything seemed to work. i ran it for a while, but its definitely not blowing as cold as it should.