96 Ram vent problems, could it be a vacuum leak?

I have noticed when my truck is under load going up hill my a/c or vent air starts blowing out through the defroster vents (I always have it blowing through the dash vents). When I reach the top of the hill or no longer have a load on the motor the air starts blowing through the dash vents. Is this a vacuum leak? Any ideas?

This isn't a vacuum leak. That's something completely different.

This is odd.

My 96 has the same problem. In a thread below it does say this is a vacuum problem below the battery try. I fixed the cracked hose yesterday, but have not got on the freeway to see if that was the problem. I will post soon if it was.

I had this problem and it turned out to be both a leak (hose under battery eaten away) and I founnd this tsb ( see below) and and bought the $5.00 check value . It works like new now!
JB
Date: Oct 18, 1996
This bulletin supersedes TSB 24-01-96

Models: 1994-1996 BR Ram truck

1993 - 1997 (ZJ) Grand Cherokee
1996 - 1997 (ZG) Grand Cherokee (international Markets)
1994-1996 (BR) Ram truck

Symptoms:

The vacuum supply to the Heater A/C System may drop when accelerating or when speed control engages. This may cause the mode vacuum motor to switch to the defrost position.

Diagnosis:

Use the procedure outlined in the appropriate Service Manual (Group 24) to verify that the Heater A/C system does not have any vacuum leaks. If no leaks found, perform the Repair Procedure.

Parts:

1 04677204 Check Valve
AR NPN Appropriate Size Vacuum Hose

Repair:

This bulletin involves installing an additional vacuum check valve.

Locate the vacuum source line to the Heater A/C system in the engine compartment (Figure 1, Figure 2). Install the vacuum check valve in the Heater A/C system vacuum line. Make sure that the check valve is installed to allow vacuum to pass into the Heater A/C system, but block any vacuum drop when accelerating.

NOTE: DO NOT INSTALL THE VACUUM CHECK VALVE IN THE VACUUM LINE GOING TO THE RESERVOIR OR THE SPEED CONTROL SERVO. INSTALLING THE VACUUM CHECK VALVE IN THE LINE GOING TO THE VACUUM RESERVOIR OR THE SPEED CONTROL SERVO WILL HAVE A NEGATIVE EFFECT ON THE SYMPTOM / CONDITION AND POSSIBLY CAUSE THE SPEED CONTROL SYSTEM TO DROP VACUUM WHILE ACCELERATING.



POLICY: Reimbursable within the provisions of the warranty.

TIME ALLOWANCE: Labor Operation No: 24-50-47-91 0.2 Hrs.

FAILURE CODE: P8 - New Part



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Thanks 95ram that is exactly what I needed.

OK, I fixed the vent problem by replacing 4 feet of Vac hose from the thing under the batter to the throttle. Now the AC vents don't go from browing on face to defrost by it's self. It didn't fix the cruse control though. Is the cable that runs with the vac hose have something to do with the it?

Yes, the unit under the battery is the cruise control servo unit, when I replaced my hose I also added the check valve at the same time since my truck didn't have one in the first place. This fixed both the vent flow problem and the cruise control problem at the same time. (my cruise control would not come on at all )
The site below has the tsb I found (and others) and has a diagram as to where to install the check valve.
It has a lot of good dodge tech info and overall help.

http://dodgeram.info/tsb/index.html

On the thread that i started I have added a picture of my cruise control servo and whats wrong with it.