Loss of power and while defrost is on....

[Duane867]

1993 Ranger 2.3L 5 speed 151,000 miles.
Can't seem to figure this out.
While the defrost is on and operating I here a click under the hood that sounds like the AC compressor clutch engaging and the truck experiences power loss while during these periods.
It does this while the defrost or while the floor/defrost settings are selected.
I'm not talking about during the selection process.

Is it normal for the AC compressor to come on during Defrost mode ?
This seems very odd to me and I would like to find out what the hell exactly is kicking on during defrost.

Thanks !

 

[scotts90ranger]

yes it is normal for the A/C to kick on in defrost, they do it so the system gets worked in the winter so it'll last longer, if you don't want it to do that, go under the hood and disconnect the clutch connector and just connect it back up in the summer when you need the A/C again...

 

[kcm1582]

yes it is normal for the A/C to kick on in defrost, they do it so the system gets worked in the winter so it'll last longer, if you don't want it to do that, go under the hood and disconnect the clutch connector and just connect it back up in the summer when you need the A/C again...

Close, the a/c operation is normal, but its done to remove moisture from the air to help clear the windshield.

 

[Duane867]

Excellent info guys ! Thank you.
I guess I'll just live with it then. No biggie.

Another question though. In neutral with the my foot off the clutch I hear a knocking noise with the AC on. Only does it with the AC on ( and the defrost on but now I know the defrost and compressor are directly related ). When I depress the clutch the knock goes away.
Does not do it at all with out the defrost or AC on though. I know the transmission is a little sloppy probably due to syncro wear ( little noisy like its not getting enough pedal some times but it is). I did the clutch, slave and throw out bearing last year but I did not replace the pilot bearing. I need to replace the transmission mount badly. I am doing that this weekend. Recently replaced the shifter bushings, retaining plate and gasket. Thought the shift rail plugs were leaking so I RTV'ed them at the same time.
Still have a leak from some where around the tail stock where it meets the main body. (Hope it isn't the gasket) I'll more then likely buy a spare to rebuild shortly. Then swap and rebuild the old one as well and keep it for a new spare.

Any info on possible causes for the knocking would also be greatly appreciated.

 

[kimcrwbr1]

yes it is normal for the A/C to kick on in defrost, they do it so the system gets worked in the winter so it'll last longer, if you don't want it to do that, go under the hood and disconnect the clutch connector and just connect it back up in the summer when you need the A/C again...

Actually the A/C is used in defrost to remove moisture in the cab during warm up. If it takes alot of power to run the pump it could be a bad bearing in the pump. I believe you can replace the pump bearing without losing the charge in the system. Worth looking into so you dont have the same problem for the cooling season.

 

[kimcrwbr1]

Turn the defrost on and put a long screwdriver on the a/c pump and see if the knock is in the pump put your ear on the handle of the screwdriver. Poor mans stethescope you can isolate lifter noise injectors and all berings just take your screwdriver or any metal rod and listen to different points the closet noise will be the loudest.

 

[kimcrwbr1]

Oh yea watch out for moving parts.

 

[Duane867]

I'd say your right about the compressor bearings.
I'll look in to a bearing kit.
Thanks!

D

 

[Duane867]

Well, there doesn't look to be any way to replace the AC clutch bearing with out loosing the refrigerant, and the labor involved combined with the cost of proper tools to do the job makes a remanufactured complete compressor look well worth the cost to me right about now LOL!

 

[scotts90ranger]

Actually the A/C is used in defrost to remove moisture in the cab during warm up. If it takes alot of power to run the pump it could be a bad bearing in the pump. I believe you can replace the pump bearing without losing the charge in the system. Worth looking into so you dont have the same problem for the cooling season.

ask 10 people the same question and 5 will say it's for drying the air, 5 will say it's to keep the system working in the winter...

 

[tomw]

I say it is to remove moisture when you get the inside of your windshield fogged up when it is raining and chilly outside. Otherwise, fresh moist air would be directed at the windshield, which would be a cold piece of glass, and it would condense.

The noise you hear may be gear rattle in the transmission. When you put it in neutral, at idle, and take your foot off the clutch pedal, the input shaft and the 'layshaft'[English] or countershaft is rotitating. It is not linked to the output shaft, so the gears just spin. As the engine idles, with the A/C compressor engaged, the load may cause the engine rpms to vary enough to slow down a bit between firing, and speed up after each plug fires. There can be enough play between the gear teeth to make them rattle as they accelerate and decelerate.
To test if that is the problem, step on the clutch while idling with the A/C engaged. If the rattle quits, you have a bit of gear lash, and you'll never get rid of it as it is normal.
To make it quiet, increase the idle speed or make sure that the IAC is working properly and adjusting the idle to make up for the load of the A/C compressor.
tom

 

[scotts90ranger]

I don't have working A/C on any of my vehicles and the defrost works fine on all of them...