Rear blower: only works on high when set on cold, won't work at all when set to heat

https://www.manualowl.com/am/Oldsmobile/1995-Silhouette/Download/972
(page #3-4 to 3-6)

Sounds like high blower relay is bad

This model has a rear heat/cold blend door actuator. Its an electric motor that moves the duct door from hot to cold. When they wear out, they're usually stuck on the last setting

There is a separate button on the lower dash labeled RR HTR for the rear heater. If you do not engage the switch it will blow cold air.

Here's a link to the blower motor resistor,usually they go bad causing you not to be able to use all speeds,it's located next to blower motor,two screws may hold it on.http://www.autozone.com/autozone/parts/2002-Ford-Taurus/A-C-Heater-Blower-Motor-Resistor/_/N-jhcdrZ91tag?filterByKeyWord=blower+motor+resister&fromString=search Here's a link to the blower motor.http://www.autozone.com/autozone/repairinfo/repairguide/repairGuideContent.jsp?fromSearchPage=true&pageId=0996b43f8036e0aa&partName=Removal+%26+Installation&partId=0996b43f8036e0aa

There is a blower motor control processor for the back blower - it takes input from the front control and the rear control and decides the fan speed. That processor could be faulty, or the blower motor, or a 30amp fuse in the engine compartment.
In the front system you have a controller and blend doors that direct air thru the heater core and evaporator. You would need to check the operation of those blend doors.

replace the blower motor and the blower motor resistor....bad motor blew out resistor and went to d\efault mode which is high setting only...good luck...Lee

flapper door inside duct work not opening and closing properly. check my tips section for heat diagrams

i have the same problem, my rear a/c blows great very cold, the front a/c blows but it is not cold at all. I had the the a/c seviced and it was vacumed and correct ammount put back in, no problems, the front still blows but it is not cold, i have checked everything and the a/c guy said it might be the door not opening. any help? still not working

blower motor resistor maybe why it only blows on high