Does anyone know how the MAX A/C setting works. All the controls on the Temp control on the console work except the MAX A/C setting. When I turn the control to this position the systems stays off. Is there an adjustment in the Temp control that needs to be tweeked?

Thanks in advance

 

Max is supposed to put the system in recirc mode where it draws air from inside the car only and not from outside.

If the system does not work at all on that setting (no blower fan, compressor clutch not engaged) I would suspect a bad a/c control switch.

 

there's a switch that turns on the compressor(like a set of contact points) and also theres a rotary vaccume switch,that takes source vaccume and distributes it to specific actuators--depending what mode you choose on the dial---when you chose max air the points should close,,,turning on the compressor at the same time the rotary vaccume switch takes source vaccume and does 2 things(does 2 things because there is a ''t'' in the line)#1 is the actuator closes the door in the wiper well and at the same time opens the door in the passenger side kick panel.....this closes off fresh air from being cooled and opens cabin air to be cooled(re-circulate mode) which means your constantly cooling cabin air,, since nothing happens when you choose ''max'' i would first look at the switch,, also i would see if the 2 actuators are working when you select ''max''you can see the one in the kick panel close when selecting ''max'' with the kick panel off(you may be able to see in there with a flashlight) --- i BELIEVE they should still operate even thou the compressor isnt ,,since these are 2 different systems vaccume and 12v power ... the fuse for the high speed should be located by the wiper washer bottle..its for high speed only,,,thats probably whats wrong if it works in every position but high

 

Two things happen on Max: 1 - The recirculation door closes to prevent outside air from coming in and 2 - the fan blower switches to high. Nothing else changes. My guess is that you aren't getting hi blower speed. Check the inline fuse (30 amp) out under the hood near the cowl. It's likely blown. Checking the recirc door is a bit tougher, and may not typically make much difference.

Steve

 

Wow you learn somthing everday on this forum. You just have to sort threw the trash. Thanks for the info carl

 

there is a very good web site for this i hope someone else can post(i had it in my favorites and its gone!!!) its called ''chadwick'' goes thru the entire vaccume for the heat/ cooling if someone can post it again lets get in in our ''favorates ''again----not to confuse you but-----there also is a ''button''type switch in the circut that will not allow the compressor to run(in any mode) if its cold out... i remember that was causing my compressor not to rum while i was working on my system(the garage was cold) i found that ''button and warmed it up with a hair dryer and the circut closed...not that thats what wrong( the compressor wouldnt run at all if that circut opens),,but i thought i'd tell ya about that also

 

Great description Carl. Since the high blower works in other modes and the vacuume lines look in the correct positions, I think the switch is more than likely the problem. I will check it out. Are there any adjustment for align the switch or is everything in a fixed location.

 

im sorry but i dont recall!! wht not open the console and jumper that puppy!---the compressor come on in the regular a/c mode right??

 

Yes,
all other modes work in low, med, and High postions.

 

well if the blower motor is not working on high-check the fuse by the washer bottle.if the compressor doesnt run on max check the switch..

 

well if the blower motor is not working on high-check the fuse by the washer bottle.if the compressor doesnt run on max check the switch..open the console and go thru the modes watching the switch opening and closing

 

Problem solved:
There is any adjustment of the switch that controls the blower mode. Looking down at the heater control, the switch assemble is located on the lower left side. The switch is mounted to a plate which is fastened by 2 screws. By loosening the screws the plate and switch assembly can move forward and backward. This moves the contact point of the switch to the control. I adjusted mine forward and now the MAX setting works properly.

Thanks for everyones comments on this post.

- Ron

 

gladi could help-what year vette did you say you have?

 

There are a couple of things here. I fixed the same issue earlier this year. Since the AC turns on and you have lower speed blower settings I suspect either the blower speed resistor or the fan relay. In my case the relay was bad. There are (3) wire wound resistors mounted in the top of the blower unit. Two screws will remove this. If those are all fine then the relay should be checked. I don't have my schematic handy, but the way I tested this was to simply use some 14ga house wire. Each speed has a unique color wire. I simply used the wire to bypass the relay and cehck each speed. With the wire every speed worked so I knew the relay was indeed bad. The new relay cost about $20. Once you have the schematic it is really quite easy to troubleshoot.