Air reserve football

[RLCollins]

The football I am referring to operates the AC, Heat, Axle shift motor on the 4 wheel drive, and cruise control. Did I miss anything? How do you properly check the football (Air reserve)behind the right bumper. From what I have gathered, it suppose to have a checkvalve in it? How long should it stay charged with air? :hmm:

[Pete M]

It's a vacuum reserve, not air. the pressure inside is negative. :thumbsup: Usually a failure will occur in the vacuum line running to it. Replace that line if it at all looks aged and cracked.

[RLCollins]

Thanks for the information Pete

Yes I realize that it is under negative pressure, meaning in a vacuum

I don't have problem with it leaking, it has 15 pounds of suction, on both the line side and the load side. There is a check valve on the line side, if I am understanding it right? This allows for a period of time with suction AFTER the motor is shut down.

Or why even have the football in the first place. Just tie the lines together and forget the football, if it really does not do anything after the engine is turned off.

It seems that it should be under a vacuum for a certain period of time, if it is an accumlator of vacuum with this check valve. So if the statement above is true about the internal checkvalve, than it only make sense. :hmm:

I have been wrong before. :chillin:

[Pete M]

The football exists so that the system can accumulate more available vacuum pressure that it would otherwise. Without it, some vehicles can have trouble operating the HVAC controls.

[RLCollins]

Thanks Pete

PS With it being the size of a grapefruit, that's small, does it really make a difference? I figured the intake manifold has more volume than that grapefruit. :hmm:

[Geonovast]

It doesn't have to be big. The ones in our trucks are bigger than most vehicles', including the one I had in my J10 with a 360.

 

There were at least two different sizes available... I believe depending on if you had AC or not.

[kro10000]

When your engine is at near to and at WOT it is developing little vacuum, so youll have issues with your vac opperated stuff when overtaking, etc

[thejum57]

Just my $0.02, when I got my Comanche the "football" was broken. I only had defrost. I got another one from a budy and relocated it above the fender well under the hood behind the battery.

[RLCollins]

Thanks for all your responses, I like thejum57 idea of bringing the football inside. Since I changed my cooling system from a closed system to and open one. I removed the pressure bottle and the self it was straped to, that was attached to the firewall. So I have room right there to install it, just above the AC fan motor, or the fender well. :chillin:

[comanche09]

I have the small grapefruit sized one (my hvac controls work great AFIAK everything is 22 yrs old).

 

The larger cylindrical "football" shaped ones come with Jeeps that have cruise control, from what I have seen during countless trips to the boneyards.

[james750]

Would it be beneficial to get one of the larger pill shaped bottles if I have a smaller ball shaped bottle? It seems to me that having more reserve vac might keep my HVAC controls running longer up the mountain passes.

[ParadiseMJ]

My XJ (90) has a football...My MJ (88) has a grapefruit...

 

The only difference between the two Jeeps is that the XJ has cruise control, the MJ does not. My understanding is that the football has 2 chambers (one for HVAC, one for Cruise) and the wall between them is solid. So basically the football is just a way to have 2 chambers without having 2 grapefruits. A uni-boob if you will.