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Both Air conditioning and Heater only work properly at high RPMs(kia rio5 2010)

Summer: My A/C would blow warm air at idle, ice cold when driving.

Winter: Heater blows cold(ish) air at idle, lukewarm when driving, blazing hot at highway speeds.

I really don’t know what to do. I’ve checked my coolant levels and I’ve checked for leaks.

Could anyone chime in? Thank you.

I had a similar condition for AC, ended up the blower motor resistor was shot, highway speeds evidently pushed enough air to make things work. Cheap and easy fix. Make sure your blower motor is actually working.

Thank you. I’ll check it out tomorrow at daytime!

Re-check the coolant level in the radiator and coolant reservoir, a low coolant level will result in the heater performance that you are experiencing. If the cooling system is full there may be a restriction in the heater core.

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Yes, check the coolant level in the radiator, not the overflow or coolant recovery tank. Do it it with a cold engine.

Like I said: I already checked the coolant levels. Thanks for the suggestions.

Could it be a bad thermostat; since both the heater and A/C are affected?

I’ll replace it anyway since it’s so cheap, I’ll report back

P.S: The A/C issue can be considered solved. Kia has made it so(for the rio5 at least) that the compressor turns off when at idle.

The a/c is fixed? Previously it did not work at idle/ low rpm. You said they fixed it so the compressor turns off at idle. That would not make it work better at idle.

??? Who said anything about ‘making it work better at idle’
What are you even on about…

I believe the OP is indicating that compressor shutoff at idle is the way the car was designed so the problem isn’t “fixed” but is now understood that this is the way the car is designed to operate.

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Yes, sir/ma’am.

That is correct.

1st post.
Summer: my ac would blow warm air at idle, ice cold when driving
What does that mean?

I means that there is a malfunction, for example if the coolant temperature exceeds 250 F the computer will disable the A/C compressor.

Nobody would want to sit at a traffic light for 3 minutes in 110 F weather without air conditioning.