2008 kia rio heat pressure reducing at lower rpm

[Sid6.7]

ok so I have a 2008 kia rio that I did a thermostat replacement and flush of the heater core on last year because of poor heat output. it now makes awesome heat but I noticed that if i am driving around town then turn into a side street the pressure from the heater reduces. like there is still hot air just there is less of it like you turned down the heat switch.

does anyone have any ideas on what I should look at?

 

[Number_35]

Air bubble in the system?

 

[Sid6.7]

Air bubble in the system?

no its not the amount of heat coming out but the force of the air. like there is lots of HOT air but not much of it being blown if that makes sense.

 

[dumkid]

Like the fan speed drops? Check your alternator output voltage

 

[Sid6.7]

Like the fan speed drops? Check your alternator output voltage

yah my alt puts out 14.88 no matter the rev range. I only noticed this last winter when it was like -40c, I turned a corner and there was no heat and the heat that was coming out wasn't that great at that time lol

I mean it was hot air after driving 20 + minutes but its was freezing cold in a **** box car so yah it sucked

 

[Jetronic]

electric power steering?

 

[SHOZ]

Sounds like air in the cooling system to me. When cold the radiator should be 100% full.

I put in a 195F tstat in my Accent for winter heat and it's the best thing I ever did. Still need to practically block off the entire radiator though. And coasting in gear will quickly drop the temps, like driving around town in the winter. Never reaches the Tstat opening point then.

Took the motor out last fall and realized it had an iron block.

 

[Rand]

what does heat pressure mean?

I take it you mean the fan slows down?
Try driving around with one of those voltage readouts plugged into the cig. lighter socket.

if its always 14.88 sounds like your alternator is malfunctioning too.

 

[GSCJR]

I think he's referring to air flow, as in a restricted cabin filter. If the blower motor speed drops when the RPM's drop, have your battery/charging system tested. It wouldn't hurt to check your connections including your grounds.

 

[Sid6.7]

Sounds like air in the cooling system to me. When cold the radiator should be 100% full.

I put in a 195F tstat in my Accent for winter heat and it's the best thing I ever did. Still need to practically block off the entire radiator though. And coasting in gear will quickly drop the temps, like driving around town in the winter. Never reaches the Tstat opening point then.

Took the motor out last fall and realized it had an iron block.

I just checked and it kind of does the same thing with the AC just not as drastic with the pressure thing

 

[Sid6.7]

what does heat pressure mean?

I take it you mean the fan slows down?
Try driving around with one of those voltage readouts plugged into the cig. lighter socket.

if its always 14.88 sounds like your alternator is malfunctioning too.

its an aftermarket alt that charges at 14.88 for my stereo system, its not the alt this was first noticed last winter on my OEM 90 amp alt not this new alt that puts out 320amps.

 

[SHOZ]

Well is the fan not blowing or what??? The faster the air speed the cooler the air for heat and the opposite for cooling. Do you have automatic climate control?

 

[Sid6.7]

Well is the fan not blowing or what??? The faster the air speed the cooler the air for heat and the opposite for cooling. Do you have automatic climate control?

this is the most basic car heating system ever think like a 1990s car. the fan speed seems the same, i mean it doesn't change in noise that i can tell.

 

[SHOZ]

It's probably just like my Accent. three speeds and has 3 dials for temp or vent selection. If the fan speed is varying then I would guess the motor. Normally it's a resistor for the different speeds and when it goes bad it just works in high speed.

Your cabin filter is clean right?

 

[Sid6.7]

It's probably just like my Accent. three speeds and has 3 dials for temp or vent selection. If the fan speed is varying then I would guess the motor. Normally it's a resistor for the different speeds and when it goes bad it just works in high speed.

Your cabin filter is clean right?

I've never even looked at it so its more than likely filthy lol.

ok so I am going to get a new fan I guess because there is something wonky going on where if you start the car and the heat is on but the fan is set to off that it starts blowing for a second then shuts off. so id guess a bad resistor sounds right.

 

[1 SX]

It was a little hard to understand what you mean by "pressure from the heat reduces" I took this a couple ways:

1) the HEAT OUTPUT TEMPERATURE gets colder at idle or on side streets. - The fan speed never changes but the TEMPERATURE DECREASES.

2) the FAN SPEED DECREASES at idle or on side streets, but the heat output is the same, just less CFM.

for 1) If you replaced your thermostat last year, did you use a OEM / Genuine T-stat. P/N HYUNDAI / KIA (MOBIS) 25500-23001 (2550023001) It is only a 180F T-stat, but is designed for the 1.6L engines. There also could be a major air pocket in the system, usually in the H/K systems, they will self bleed the rest of the air out, if you get a majority out first. Also what ratio and type of coolant are you using? a 60/40 mix might give you slightly more heat. If all else fails, you could upgrade to a 192-195F t-stat.

for 2) Most H/K charge at 14.2-14.4V and not much more than that... If your fan speed decreases, but yet you are charging at 14.8V or more your volts might actually be TO HIGH, and can cause damage to the electronics (resistor ect). Also change the cabin air filter behind the glove box. if restricted, you will have less CFM overall.

 

[1 SX]

its an aftermarket alt that charges at 14.88 for my stereo system, its not the alt this was first noticed last winter on my OEM 90 amp alt not this new alt that puts out 320amps.

keep in mind most aftermarket alts do not output anywhere near the stated amps esp on cheaper units...

I have the factory alt in the Kia, and run some watts with 2 separate amplifiers. I installed a capacitor to not cause the electric spikes. Even with the amps at full bore, with all lights on, heated seats, heat and rear window defroster, basically max load, there is ZERO dimming of the lights, even at 675 rpm idle.

 

[Sid6.7]

It was a little hard to understand what you mean by "pressure from the heat reduces" I took this a couple ways:

1) the HEAT OUTPUT TEMPERATURE gets colder at idle or on side streets. - The fan speed never changes but the TEMPERATURE DECREASES.

2) the FAN SPEED DECREASES at idle or on side streets, but the heat output is the same, just less CFM.

for 1) If you replaced your thermostat last year, did you use a OEM / Genuine T-stat. P/N HYUNDAI / KIA (MOBIS) 25500-23001 (2550023001) It is only a 180F T-stat, but is designed for the 1.6L engines. There also could be a major air pocket in the system, usually in the H/K systems, they will self bleed the rest of the air out, if you get a majority out first. Also what ratio and type of coolant are you using? a 60/40 mix might give you slightly more heat. If all else fails, you could upgrade to a 192-195F t-stat.

for 2) Most H/K charge at 14.2-14.4V and not much more than that... If your fan speed decreases, but yet you are charging at 14.8V or more your volts might actually be TO HIGH, and can cause damage to the electronics (resistor ect). Also change the cabin air filter behind the glove box. if restricted, you will have less CFM overall.

it does the same thing with the AC on so its not the thermostat and it was doing the same thing last year on the 90 amp alt the aftermarket one has only been installed for like 2 weeks and the car hasn't been driven.


I guess its the fan speed decreasing when the rpms lower but it will give full fan speed sitting in the driveway

 

[Sid6.7]

keep in mind most aftermarket alts do not output anywhere near the stated amps esp on cheaper units...

I have the factory alt in the Kia, and run some watts with 2 separate amplifiers. I installed a capacitor to not cause the electric spikes. Even with the amps at full bore, with all lights on, heated seats, heat and rear window defroster, basically max load, there is ZERO dimming of the lights, even at 675 rpm idle.

you do realize that capacitors do nothing right? for them to do anything you would need a massive capacitor bank and then it would be drained after one bass hit anyway. I also have the amp dyno for my alt and you can't get a cheap aftermarket alt for these cars.

 

[1 SX]

you do realize that capacitors do nothing right? for them to do anything you would need a massive capacitor bank and then it would be drained after one bass hit anyway. I also have the amp dyno for my alt and you can't get a cheap aftermarket alt for these cars.

to each their own... but you do realize your most likely wrong on that one... This is stated right from Cruthfield and hand on results.

Q: What's a capacitor?
A: A capacitor, or cap, is an electronic component that can take up, store, and discharge electrical energy. Because they can do all that quickly, capacitors are used to filter or buffer any sudden changes in a circuit's voltage, smoothing the ensuing signal.

Q: What's a capacitor used for?
A: In car audio, large outboard capacitors, sometimes called stiffening caps, are used to prevent lights from dimming when loud bass notes play. They accomplish this by supplying the amplifier with a quick jolt of power.

Q :HOW DOES A CAPACITOR WORK?
A: Stiffing capacitors store electricity, which they can discharge very quickly unlike the vehicles battery and alternator. They give your amplifier quick jolts of power when the bass hits to cover the amount of current it requires for musical transients. This ensures the amplifiers in your car are properly supplied and working at peak performance.

In regards to the FAN SPEED DECREASING at idle: Check: CABIN AIR FILTER - if dirty would have decrease in CFM because of extra air resistance passing over a blocker filter... FAN RESISTOR, AND maybe FAN PIN VOLTAGE.. Also I still believe 14.8 PLUS volts is a little too high.. H/K prefers it closer to 14.0V-14.3V... Charging at almost 15 volts all the time will shorten your battery life also.

But if the FAN SPEED DOES NOT INCREASE OR DECREASE with the switch, it could be the RESISTOR .... basically it would be one speed no matter what number you selected if that was bad (on/off)