Crunch PD 1000 3 channel mode problem

[AnalogKidGloves]

hi everyone
I have this crunch pd 1000 amp and when in 3 channel mode sound output thru the door speakers seems to be in mono.No change in volume when balance on head unit is turned all the way to left or right. When amp is switched to 2 channel mode, balance control works fine...when all the way to the left no sound from right speaker and when all the way to the right no sound from left speaker. Tried 2 different head units, a Sony CDX M501P and a Sony CDX M8800…same thing happens.
I have it wired 4 channel mixed mono. Crossover mode switch for channels 1&2 is on HPF and on channels 3&4 its on LPF. Front low level L and R outputs from head unit going to channels 1&2, sub outputs from head unit going to channels 3&4. Channels 1&2 output to left and right door speakers. Channels 3&4 output bridged with L channel positive output to positive terminal of sub and negative terminal of sub going to R channel negative output...just like in the diagram.
So is my amp toast? Any info will be greatly appreciated. Thanks!

 

[Perry Babin]

How do you 'switch' to 2-ch mode?

 

[AnalogKidGloves]

by selecting 2 channel on the MODE switch

 

[Perry Babin]

What happens if you connect it you showed but use the 2-channel mode?

 

[AnalogKidGloves]

There's no sub output when its in 2 channel mode

 

[Perry Babin]

Isn't 2-ch mode supposed to feed all channels?

I couldn't find the manual for your amp. I was using the manual for a similar model.

If you leave it in 2-ch mode and feed channels 3 and 4, which channels have audio.

 

[AnalogKidGloves]

all the channels have audio when 3 and 4 are connected to the sub out

 

[Perry Babin]

Is the end panel incorrectly marked?

 

[AnalogKidGloves]

It sure seems like it. That never crossed my mind...does it happen that often? Anyway I have it hooked up now 2 channel mode with the sub volume turned up to +3 on the head unit and everything sounds fine. Thanks for the help. Its going back in my truck today.