2005 jeep wrangler heater was only blowing out of defrost. found vacuum line unplugged the vacuum line runs along the firewall into a tee then under battery.hooked line up then engine wants to surge but fixed heater.was going to find other end of line to see if it is cracked.unhooked line, heater still works and no engine surge .the line was unhooked from intake.thanks for your help

Well this is different since most questions now are about no heat.
If one ac line is cold and the other is warm, I would suspect a blend door under the dash is not working. The blend doors direct air thru the heater core and the vents.

The mode control on your heater panel uses engine vacuum to operate the doors in the heater box. when the system loses vacuum, it defaults to the defrost setting. find the small plastic vacuum line that penetrates the firewall and leads to the engine intake manifold. Check the hose that attaches the line to the engine for cracking or looseness. If that is OK, trace the line back into the cabin. It should lead to the control panel. Check any tees or couplings for leakage. If it's good all the way to the mode control switch, it is likely the connection to the switch or the switch itself is leaking. With the engine running, listen carefully to the switch for hissing. It is also possible that the defrost door actuator is bad. If you can find the door, try applying vacuum directly to the actuator to see if it operates to shift the flow. If it doesn't, replace the actuator.

the control is the dash switch most of the time the vacume hose gets knocked off the engine when this happens the heater defalts to defrost check under the hood for a small hose coming out from the firewall

Open your hood and find a "T" connector right near the battery. Follow the line down below the battery (you will have to get under the Jeep). You will see that the line plugs into a 3 to 4 inch section of 3/16" tubing that is plugged onto a black in color, plastic box. Use a razor knife and trim off about 1/2" of this 3/16" tubing as it commonly cracks where it fits on the nipple of the black plastic box. The vacuum cannot build pressure properly with these cracks in this tubing, and therefore cause the selector door to malfunction when operating heat and a/c. It is a quick and easy five minute fix.

Check under your hood for a loose or leaking vac line , The A/C system on your jeep uses manifold vac to move the air mix doors and with no vac the air mix door will move into the defrost position. Find your vac leak and that will fix your problem.

The AC functions of defrost, vent and floor are controlled by vacuum motors, you have a vacuum loss problem from the engine, check for a small disconnected vacuum hose under the hood from the engine to the firewall..

This is a vacuum problem. Under the hood on the pass. side by the firewall there is a vacuum line that feeds the heater doors. This line is either disconnected or broken. These cars also have a vacuum resoivor that stores vacuum, this could be broken or leaking vacuum.

is it blowing threw the defroster if it is open the hood look on the left hand side of the fire wall there is a vacuum line there if it is broke blower will only come through defrosters if you have a vac canister it looks like a ball make sure the vacuum lines are good on it

You have a broken vacuum line to the dash panel control.
Look under the hood on the pass. side next to the firewall.
You will see some vacuum lines, maybe one came off?

you have managed to disconnect a vacum hose either under the dash when you instaled the blower or you have disconnected the vacum hose under the hood close to the firewall look for ths hose it is a very tiny vacum hose!!!!