Heater not working

I was useding my air conditioner in the pass and when it got cold I had no heat my I think condenser and air con. Hose would be dripping water with the heat on is there a relay or vacuum to switch it back n fore I hope u can help

When the gauge was on the hot side all that I was getting was cold air. I watched the gauges to see if it was over heating. Everything was right. Is the gauge that controls the hot and cold side need to be replaced?

Thank you for your help,
Duane

Hose on the passenger side - hot
hose on the driver's side - cold

please advise

Blowing cool air, had it flushed and still blowing cold air. Its not over hearting and runs great.

Not sure if I have one issue or two. 2004 Chevy blazer, heater blows cold air ( pronoun initially random and only occurred about every 3rd or 4th time I started vehicle, gradually became worse over a month or so, now only blows cold air. Additionally, during warm weather, air conditioner blows good cold air, however auto overheats if outside temperatures are above approx. 75°. Turning air off does little to help reduce overheating. Have replace thermostats 3 times, replaced water pump and have had radiator flushed and checked out by a mechanic. Was told no issues with radiator. Not sure what issue is out where to turn next. Is this a common issue? Could it have something to do with heater core? Do I have two separate issues or are they related? If any idea on problem, what is estimated repair costs? Appreciate any assistance. Mammastone

My heater seems to work internmittently. Sometimes it is really hot and sometimes not at all. The other day it was too hot so I turned the temperature down and then it got cold and when I turned it back up again it would not get hot again. I purchased this car in mid-summer this year and know that it has had a fornt end accident in its history.

I had to have fan motor under dash replaced. Air blows out top vents and windshield.
But nothing on feet. No heat or air on feet. I called one mechanic he said it would cost
$800 have take whole dash out find problem. It that what has to be done to fix?
Thanks Mike

Recently when driving, less than ten minutes the engine will overheat almost to the max red line. I turned on the heat, and no hot air comes out, it just blows cold. I was on my way to work and kept going, then the temperature gauge dropped to 3/4 (still 1/4 way to max hot) and stayed there. The first day lots of steam came out before it cooled. Now steam is not coming out, but all other issues remain. Is this just a thermostat, or likely something else?

When the car is 1/4(Gauge) warm to 1/2 heater air is warm. Once the car reaches normal temp. The air is cold if the rpm drops below about 1700 rpm. Heater core is not clogged, runs freely and hoses are same temp. In and out.