I purchased a Polaris 3900 on 6/2/2010 and have already replaced two filter bags. Both times the bag has become wedged between the chasis and the wheels tearing the bags. Any suggestions?

blocked wand hose or head
there is no air flow to cool the motor
replace bag if it has one
replace filter in a bag less unit

The dust bag holder is an important part of this vacuum. Make sure the bag is installed into the holder sliding bag collar into slots to secure.
Make sure the bag is tucked into cleaner. or the bag cover will not latch securely.
Also, the motor and exhaust filters should be cleaned at each bag replacement.
REPLACING THE FILTERS
Filters should be cleaned or replaced when they become visibly soiled or suction power is reduced. Always operate the cleaner with the filters installed to avoid motor damage. The dust bag must be changed and the filters cleaned or replaced if the window of the Clean Filter Indicator changes into red when the cleaner is operating at maximum power and the nozzle is raised from the floor.

The dust bag holder is an important part of this vacuum. Make sure the bag is installed into the holder sliding bag collar into slots to secure.
Make sure the bag is tucked into cleaner. or the bag cover will not latch securely.
Also, the motor and exhaust filters should be cleaned at each bag replacement.
REPLACING THE FILTERS
Filters should be cleaned or replaced when they become visibly soiled or suction power is reduced. Always operate the cleaner with the filters installed to avoid motor damage. The dust bag must be changed and the filters cleaned or replaced if the window of the Clean Filter Indicator changes into red when the cleaner is operating at maximum power and the nozzle is raised from the floor.

Check the bag of your pool cleaner to make sure that it doesn't have any holes or tears that should not be there. Some fine particles will not be picked up by pool cleaners, no matter how effective. If your filter is not catching the debris, you might need to manually brush the bottom and sides in order stir the dirt up into the filter.

There are six different reasons a vacuum can lose suction, a plugged vacuum hose, bad motor, full vacuum bag, or cracked or damage hoses. Purchasing a vacuum cleaner can be a costly expense while repairing the suction on the unit can be virtually free. Most suction loss problems on a vacuum can be easily fixed or remedied with common house hold tools and very little technical expertise.
If your vacuum cleaner losses suction, the first and easiest solution is to check the bag. If the vacuum cleaner bag is full suction will be greatly reduced and the unit will become ineffective. A vacuum cleaner works by passing air through the bag fibers leaving dirt and debris behind inside the bag. If the refuse bag becomes full, airflow is restricted, limiting the amount of air passing through the vacuum bag resulting in loss of suction. When replacing the vacuum bag always consult your owners manual to insure that the vacuum bag seals with the vacuum inlet hose. If your vacuum cleaner bag is not tightly sealed to the vacuum inlet hose you will decrease the air flow through the bag resulting in loss of suction.
The second and sometimes most common reason for loss of suction on a vacuum cleaner is a plugged vacuum hose. If the hose becomes plugged, air flow will become restricted. To unplug a vacuum hose detach it from the machine and inspect the inside. If there is a restriction in the hose, remove it with your fingers and replace the hose onto the unit. If the hose is long and the debris is hard to get too, a broom handle or other long object can be passed through the hose to dislodge the debris. Most vacuum cleaners contain more that one suction hose, so make sure to check each one by process of elimination. Another area that can become easily plugged on a vacuum cleaner is under the lower base of the unit by the roller brush. Large debris can get caught in this area and restrict air flow to the hose.
If your vacuum refuse bag is not full and the suction hoses are not plugged the next thing to check is the condition of the hoses. Many hoses are made from plastic which can easily tear or crack. If your vacuum cleaner shows signs of wear or are cracked they need to be replaced. Even the smallest hole in a vacuum hose can leak enough air to greatly diminish the suction potential of your unit. Replace your vacuum cleaner parts with OEM parts from the original manufacturer to ensure the tightest fit.
Most vacuum cleaners contain filters. Filters are used as a last line of defense to remove dust and smaller debris particles before the air is recycled back into the environment. If vacuum cleaner filters become dirty or plugged they also can decrease the amount of air traveling through the unit. Some filters can be easily rinsed with water whereas others need to be replaced. It is important to check your owners manual before rinsing a vacuum filter.
The last and probably least common problem for a vacuum cleaner to loose suction is a bad or failing vacuum motor. Over time vacuum motors lose power due to worn carbon brushes or long term damage. A vacuum cleaners worst enemy is moisture. If water or moisture is sucked into the vacuum motor it will greatly diminish the amount of suction the unit has. Replacing a vac motor can be a costly and time consuming ordeal. In some cases, replacing a vacuum motor can outweigh the cost of buying a new vacuum. Vacuum suction is measured in water lift which can easily be measured by using a water lift gauge. If the water lift measured in inches, falls below half the original water lift specifications for the unit, it is time to replace your motor. Most vacuum cleaner repair shops carry this type of equipment and can easily tell you if it is time for a new vac motor.

There are several things that you can check on these automatic pool cleaners to try and correct this problem. First, make sure that the filter bag is not full. A weighed down bad can cause the cleaner to tip onto the nose. If there is water in the head float, you will need to replace it. Make sure your hose floats are spaced correctly so that they are not causing the cleaner to float incorrectly.

CONTACT SUPPLIER OF SADDLE BAG FOR REPLACEMENT OR IMFO WHERE TO GET ONE.

Sometimes the wiring under the passenger seat can become compromised from objects in floor becoming wedged under the seat.May need to be reconnected if possible..Usually if the air bag light remains on , it means the air bag will not engage if needed. Should have the dealer service department check for you.