A/C Clutch Relay Jumper

[6herald6]

On my '05, 3.0L I want to jumper the a/c relay (46a) to see if it engages the clutch. The relay diagram shows it uses terminals 1, 2, 3, and 5. Which two of these are jumpered and how are the relay slots numbered? Thank you for your help.
Fred

 

[franklin2]

Jump 3 to 5. I would check for voltage on 3 to make sure fuse 25 is still good.

Not sure how the numbers relate to the relay socket, but if you use a testlight, with the key off, only one terminal will have power (if the fuse is good) and that will be terminal 3.

If you take a meter and put it on ohms rx1, unplug the connector at the clutch, and put one meter lead on the grey/white wire. Take the other meter lead and probe each remaining terminal in the relay socket. You should already know which is terminal 3. When you get a near zero reading, that will be terminal 5.

So since you have power on terminal 3 at all times, and terminal 5 goes directly to the clutch, you can jump these two you found and it should engage.

 

[6herald6]

Thanks, franklin2, I'll get at this tomorrow and see how it turns out. I had the cylinder heads replaced a few years ago and the a/c started to take longer and longer to get cold since then. I think the system might have been compromised during the heads exchange.

 

[franklin2]

The most common failure is a slow leak in the system. Turn the A/C on with the truck running and then pull the low pressure switch connector out and jump the terminals. If it runs, you are probably low on refrigerant. Some leaks are very slow and a quick recharge with a can from Walmart will last a couple of years. Some leaks are a little larger, I have had them were 1 can would last through the summer, so I would have to add a can every year. And then some leaks are severe, and it won't last but a couple of days.

 

[6herald6]

Thanks again, franklin2. I will check this all out and look for the leak. Also, if the clutch engages with this jumper can I recharge the system in this manner?

 

[franklin2]

Thanks again, franklin2. I will check this all out and look for the leak. Also, if the clutch engages with this jumper can I recharge the system in this manner?

Yes. You can hook the can up and let the refrigerant into the system as much as it will go, and then you can jump the switch and the compressor will suck the rest of it in. If you want to speed up the process, once you get the compressor going you can turn the can upside down for a instant, and then turn it back upright so the hose is on top. You can do this again and again, I would not hold the can upside down for a long time though. You are letting liquid refrigerant into the system with the can upside down, but you don't want too much liquid in it, it may make its way to the compressor and lock it up. The compressor can only handle gas. But short bursts of liquid will speed the filling process.

Once you get half the can in there, the compressor might run by itself without the jumper. On most Fords the low pressure switch also controls the cooling. I am not sure where you live, but if it's cool weather, the low pressure switch may cycle the compressor clutch, even though it's full. It's best to fill the system when it's at least in the high 70's. You want lots of warm air going over the coil, that will keep the pressure high on the low side, and the pressure switch will not cycle the clutch if there is plenty of refrigerant in it.

 

[6herald6]

Yes. You can hook the can up and let the refrigerant into the system as much as it will go, and then you can jump the switch and the compressor will suck the rest of it in. If you want to speed up the process, once you get the compressor going you can turn the can upside down for a instant, and then turn it back upright so the hose is on top. You can do this again and again, I would not hold the can upside down for a long time though. You are letting liquid refrigerant into the system with the can upside down, but you don't want too much liquid in it, it may make its way to the compressor and lock it up. The compressor can only handle gas. But short bursts of liquid will speed the filling process.

Once you get half the can in there, the compressor might run by itself without the jumper. On most Fords the low pressure switch also controls the cooling. I am not sure where you live, but if it's cool weather, the low pressure switch may cycle the compressor clutch, even though it's full. It's best to fill the system when it's at least in the high 70's. You want lots of warm air going over the coil, that will keep the pressure high on the low side, and the pressure switch will not cycle the clutch if there is plenty of refrigerant in it.

Alright. This weekend I will get at this if the weather is warm and sunny as it has been this week in the L.A. area.
Thank you, franklin2