No temperature control

[Nomadster]

Hi , My 97 Ranger XLT only blow's hot air & i only have two speed settings on my fan..the 2 highest ones . I've read many post about the possible causes and fixes eg. blend door etc.......before i attempt any I'm wondering if anyone can tell me why when i first start my truck i can hear a "clunk" in the heater box as if a door/flap is either closing or opening . Is this normal ( my 1990 ranger never did this ) or could this be something pointing to my problem with only blowing HOT AIR !!??
Any help greatly appreciated.
Tks D.
PS: EXCELLENT ARTICLE on here for simple /quick blend door fix by "MAGICLAND"

 

[TheJackal]

The fan speed problem is probably a bad resistor. This seems to be common.

As far as hot air goes it could either be the blend door, or you could be having an A/C sealed system problem. Do you know if the underhood components of the A/C system are in good shape? When the A/C is on and has been running a while, does the black canister near the passenger side firewall get cold?

 

[Nomadster]

Hi & Tks for the reply.....i did suspect the resistor for the fan speeds but i haven't checked that canister to see if it gets cold..i do know that my AC works on Max A/C only....i just didn't know if i should hear that clunk as if a flap/door was opening or closing ?? . I will check that canister .
D.

 

[austinmob]

I have a similar issue. Onlys blows hot air even with the AC on. The noise under the dash sounds like a hatch closing. I'm assuming its the vent flap or something. To stop the hot air i tied up (manually closed) the valve control unit which is located on the inbound heater hose. There is a small air tube type hose which fits onto the valve and it doesnt appear to do anything, i took it off. Whether its on or off makes absolutley no difference. I think its supposed to suck the valve shut when the AC is switched on but it does not. As for my switch, well it doesnt matter where it is, the AC comes on for every setting.

Come winter (very soon) i have to untie the hot water valve control unit to get some hot air in the cabin.

My condensor unit gets cold so apart from the above it seems to work fine.
Is this what yours is doing. Have you tried manually closing the hot water valve.

 

[TheJackal]

Cold air only in "Max A/C" mode or when the heater core is otherwise bypassed indicates a blend door failure. See here:
http://www.explorerforum.com/forums/showthread.php?t=214332
http://www.explorerforum.com/forums/showthread.php?t=193991
http://www.explorerforum.com/forums/showthread.php?t=59787
http://www.explorerforum.com/forums/showpost.php?p=1299245&postcount=7
http://www.explorerforum.com/forums/showthread.php?t=133641
http://www.explorerforum.com/forums/showthread.php?t=212667
Also See Here:
http://www.chrisfransen.com/Ford_Blend_Door_Fix/index.html

Don't worry about the canister; if you get cold air on Max A/C there is nothing wrong with the sealed system.