You must open the hood. Now check for a rubber drain hose coming off from the firewall. You will most likely have to unclog the hose as it is typical to become filled debris.
To unclog the rear AC drain hose on a 1993 GMC Suburban, first locate the hose, which is typically found under the vehicle near the rear passenger side. Use a wet/dry vacuum to suction out any debris or blockage in the hose. If that doesn’t work, a flexible wire or a plumber's snake can be inserted gently into the hose to dislodge the clog. Finally, flush the hose with water to ensure it is clear and functioning properly.
Fabricate and adapt a smaller hose to your vacuum cleaner and attach the smaller hose to the drain tube to suck out the debris. You could blow it in with compressed air but then the debris will only plug it up again.
Go underneath where the drain tube comes out and blow air up the hose. It may clog again, often there is a build up of sludge in the evaporator case that plugs the drain. What I do is, use a length of rubber hose such as a neoprene fuel hose that fits tight over the drain tube, then adapt the other end to my shop vac and suck out the debris.
Go to ace hardware or homedepot and get a drain king. It is a water bladder that you put on your hose. remove the PUMP lid from your pump and place the drain king into the top hole turn on the hose and let the pressure clear the line
The evaporator drain hose is in front of the center console at the bottom... if you pull back the carpet just to the right of the accelerator pedal, you'll see a white fitting pressed into the driveshaft tunnel with the hose connected. The hose runs to the bottom of the evaporator housing. From under the car, the outlet is hidden by a heat shield for the catalytic converter. Bend back the right front corner of the shield to access the drain.
there is no drain plug.just remove bottom radiator hose
siphon It out with a cut garden hose..
Drain the radiator and remove the hose and remove the clog. I suspect you have other problems if you think the hose is clogged. I would suspect the thermostat is stuck closed. Replace the thermostat and flush the system.
The heater uses the engine coolant to heat the vehicle. The radiator has a drain petcock along the bottom edge to drain the coolant system.
Remove the bottom hose to drain the system. Remove the top one as well and flush from the top with a brisk flow from a hose pipe.
Get under the car and locate the drain valve or disconnect the lower water hose.