You would think that a company such as Chrysler would be able to build something that at least made a tiny bit of sense.......but NO.... If you want to fix something as simple as HOT AIR in the car you have to take the whole car apart.
So, now that I've vented here is the website that will answer your question (and cause you to wonder why you bought a Jeep in the first place) Go ahead, bang your head on the driveway......but this is the true stuff:
http://www.wjjeeps.com/hvac_sub_assembly.htm
Your climate control in your 1998 Ford E250 Cargo Van blows cold air when in heat position and sometimes it blows warm air when in the cold position?
You have the digital temperature controls and the little doors inside the heater box(behind the dash assy) are broken. The only way to repair this is to pull the dash and the heater box assy out. This will not be a cheap repair--at least $500.00-$1000.00. Sorry for the bad news.
The HeaterTreater is an after market kit that solves heater and AC blend door malfunctions for the Jeep Grand Cherokee and Laredo. It is much cheaper than the dealership fix and is easy to install. For diagnosis and info, check out www.heatertreater.net or search eBay for "heatertreater".
The most common problem with heat on these cars is a broken blend door. The dealership will want a fortune to repair it but there is a do it yourself alternative kit out there called the Heater Treater. Check them out on google and ebay and go to the site for full diagnosis and info. They have solutions for both single control heat and dual control heat...hope this helps!
I would look for a Vacuum leak possibly under hood. Does your Cruise control work?
Check your climate control switches, and vaccuum lines. If you have electronic climate control, you probably need to have it serviced. Quite often in Grand Am's 91-2002 have had minor problems with weak linkages within the housing and routing of the climate control rod's and lines.
The most common issue is the heater / climate control valve. This can usually be tested in dual mode and checking for change in air circulation.
This may be a cause... My wife's 95 contour had to have the vacuum temp settings control unit replace 2 times. If you are constantly changing settings it really blows the valves in the climate control center... Just a thought.
either your heater control valve is bad or you heater control switch on your dash is broken pull the knob of and see if it is cracked.
you may need to recharge your system My system is charged and has no leaks. Could it be my climate control module??
it could be your thermo stat
control fuse blows when you plug thermostat to base controlling a gas pack unit