Engine/Transmission (1998.5 - 2002) Still chasing my APPS problem

[DLBurns]

Here is the latest, only get the codes and CEL when the AC compressor cycles. Disconnected the AC compressor at the connection and cleared the codes, turned on the AC selector switch and set the code and CEL again with the AC compressor disconnected

Took out the AC clutch relay, low & high pressure cutout switches, cleared the codes & CEL. Replaced the AC clutch relay. . no codes or CEL, reconnected the low pressure switch. . no codes no CEL... . connected the high pressure cutout and set the codes and CEL! OK now it either the high pressure or low pressure switch... replaced them both and turned on the AC... codes are set and CEL is lit the minute the AC compressor cycles

AC Compressor cycles on and off every 7 seconds, Cliffman was assisting me and we checked his 01' and his AC compressor kicked on and never cycled once while we watched it???

Man I am at my wits end with this thing... ANYONE out there experience anythng like this that could point me in the right direction?

I have spent $650. 00 bucks and a whole bunch of time trying to pinpoint this problem, I'm starting to feel like a dealer, just keeping dumping money into it until the problem goes away

 

[Gary - K7GLD]

How/where do those AC sensors ground? Is there possibility one or both have a poor ground return somewhere in their path? Does the AC function properly otherwise, I'm sorta confused about the AC compressor cycling evey 7 seconds... Could the instantaneous current draw of the AC clutch be setting the code due to low electrical system voltage - don't recall other comments on this issue, so dunno if your batteries are new or not...

 

[MACHINEST]

Hey Buff,if an AC compressor cycles like yours does it's usually low on freon,but i don't see what that would have to do with setting codes. . and like Gary said you may have a bad ground some where...

 

[rkressg]

Any time I have seen an AC compressor switch on/off like that, it was low on freon. If it is low, don't forget to add an oil charge with the freon. You don't want to fry the compressor.



-Rich

 

[MACHINEST]

Buff, If the clutch is kicking in you would have a ground,because no ground no kick in,the low switch is hooked in with the high pressure switch,now if it gets to low on 134A the low pressure switch is suppose to drop the circut to your clutch,and the same way with the high pressure switch,if the pressure gets to high it will drop the clutch but it takes it a lot longer to kick in,but if the pressure is to high it will cycle the clutch,if it is to low on 134 A it will cycle the clutch,if it is cycling real fast,i would say it is low on freon,because if it were to full of freon,you would have to wate till the high pressure bleads off for the circut to make,and your clutch kick back in,it sound like your problem may be in your PCM,do you have any body with the same truck that you can switch them out? And i would put a set of gages on the AC that way you know where your at there,I hope this helps...

 

[Cliffman]

At this point everything seems to point to the PCM... Might not hurt to check the freon. If in fact it is the PCM I wonder how/what would have caused the PCM to go bad. We do have a friend who is willing to let us use his PCM but we’re concerned that what ever caused this PCM to go bad might also do the same to the loaner. That would not be good :{

 

[DLBurns]

How/where do those AC sensors ground? Is there possibility one or both have a poor ground return somewhere in their path? Does the AC function properly otherwise, I'm sorta confused about the AC compressor cycling evey 7 seconds... Could the instantaneous current draw of the AC clutch be setting the code due to low electrical system voltage - don't recall other comments on this issue, so dunno if your batteries are new or not...

Gary,

I just put in two new Optima Red Tops as well as a new Apps, and High & Low AC pressure switches. The ground for the cutout switches is located on the left side of the block under the fuel pump and I have not checked that one yet ( one of a couple of hundred grounds on this thing ) There is also a ground for the AC/Heater switch behind the dash above the radio compartment that I haven't checked yet. I had a radio installed a year or so ago, wouldn't think it would take this long to show up if there was a problem there, who knows, maybe something worked loose

Keep the ideas coming, I will CHECK ANYTHING to solve this mystery!!

Dave

 

[MACHINEST]

The only thing that would cause a loaner to go bad,would be if you had a hot wire shorted to ground... Don't Know... . But there is a lot of electronic pcs to go bad in an PCM... . Has she ever been Jump started or have you ever jump started some one else,some times an arc will do great things,also low voltage on batterys aren't good... .

 

[DLBurns]

Buff, If the clutch is kicking in you would have a ground,because no ground no kick in,the low switch is hooked in with the high pressure switch,now if it gets to low on 134A the low pressure switch is suppose to drop the circut to your clutch,and the same way with the high pressure switch,if the pressure gets to high it will drop the clutch but it takes it a lot longer to kick in,but if the pressure is to high it will cycle the clutch,if it is to low on 134 A it will cycle the clutch,if it is cycling real fast,i would say it is low on freon,because if it were to full of freon,you would have to wate till the high pressure bleads off for the circut to make,and your clutch kick back in,it sound like your problem may be in your PCM,do you have any body with the same truck that you can switch them out? And i would put a set of gages on the AC that way you know where your at there,I hope this helps...

Why would it set the code and CEL with the compressor connection un plugged

I am hoping it is not the PCM, but it's looking more and more like that is the culprit! I have a set of AC gauges ( don't know how to use them? ) that I found, are all of the gauges compatable with R-12 & R134A??

Like Cliffman said, I do have a friend in our club who is willing to swap me PCM's for a test drive but I am worried about whatever is causing my problem doing the same to his his PCM!! I would then have to buy two new PCM's which I would prefer not to do as I am already hemmoraging money on this damn thing!!

Thanks for the suggestions and keep them coming, I am getting desperate! I don't want to take it to the dealer unless I have too as they will rape me for diagnostics

Dave

 

[DLBurns]

The only thing that would cause a loaner to go bad,would be if you had a hot wire shorted to ground... Don't Know... . But there is a lot of electronic pcs to go bad in an PCM... . Has she ever been Jump started or have you ever jump started some one else,some times an arc will do great things,also low voltage on batterys aren't good... .

Never jump started anyone, and batteries are less than 2 months old!



Thanks for the info on the PCM though, puts my mind more at ease as far as trying another one.

Dave

 

[Cliffman]

Hey Dave, I wonder if it might be a better idea to try your PCM in our friends truck to see if it throws the same code???? Don’t see how it would hurt his truck and that way you don’t have to worry about buys 2 PCM’s…

 

[Gary - K7GLD]

"Hey Dave, I wonder if it might be a better idea to try your PCM in our friends truck to see if it throws the same code???? Don’t see how it would hurt his truck and that way you don’t have to worry about buys 2 PCM’s…"



Well DUHhhhh! :-laf



Now why didn't some of us other dim bulbs think of that! :-laf :-laf



ANYWAY, here's a possble source for a replacement PCM, if needed:



http://cgi.ebay.com/ebaymotors/ws/e...0910327&rd=1&ssPageName=WDVW#ebayphotohosting

 

[DLBurns]

"Hey Dave, I wonder if it might be a better idea to try your PCM in our friends truck to see if it throws the same code???? Don’t see how it would hurt his truck and that way you don’t have to worry about buys 2 PCM’s…"



Well DUHhhhh! :-laf



Now why didn't some of us other dim bulbs think of that! :-laf :-laf



ANYWAY, here's a possble source for a replacement PCM, if needed:



http://cgi.ebay.com/ebaymotors/ws/e...0910327&rd=1&ssPageName=WDVW#ebayphotohosting

Not sure I want to set a code in someone else's truck unless I have the scanner handy to clear it!! We'll have to see what Brad thinks.

Thanks for the link Gary.



Anyone else have ideas or suggestions, at this point I am willing to look into anything!!!