Ac not as cold when car warms up

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Miggy
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Joined: Mon Nov 04, 2019 12:08 am

Ac not as cold when car warms up

Postby Miggy » Fri Nov 22, 2019 11:09 pm

Hey guys, i have a new problem with my car ac that just showed up recently. The ac performance decreases as the car warms up.

These are the readings with the gauges i bought:

Car in the garage, cold start:
Vent temp 12.5 degrees celsius (at least according to my cheap digital thermometer)
Low side pressure: 25 psi
High side pressure: 175 psi
Ambient temp is at 25 degrees celsius (at least according to my cheap digital thermometer). The weather app on my phone says 27 degrees celsius.

After driving the car around for awhile:
Vent temp: 16 degrees celsius
Low side: 28 psi
High side: 185 psi
Ambient temp is still at 25 degrees celsius. The weather app on my phone says 27 degrees celsius.

All of the readings at idle speed, max fan speed and in my garage.
The car isnt overheating, both fans are working. The condenser fan motor has been upgraded to a two speed one running at high speed with ac on.

"New" used evaporator, new txv and reciever drier.

Any ideas why this could be happening? Thanks.

Oh, and i also checked the heater blend door, its completely closed with the knob at max cold.
Dougflas
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Re: Ac not as cold when car warms up

Postby Dougflas » Sat Nov 23, 2019 6:04 am

Clamp off the heater.
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Cusser
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Joined: Sun Apr 24, 2016 6:29 am

Re: Ac not as cold when car warms up

Postby Cusser » Sat Nov 23, 2019 8:17 am

Miggy wrote:Hey guys, i have a new problem with my car ac that just showed up recently. The ac performance decreases as the car warms up.

These are the readings with the gauges i bought:
All of the readings at idle speed, max fan speed and in my garage.


I'd like to see both low and high pressures at about 1800 rpm. Idle is not where to test.
Miggy
Posts: 23
Joined: Mon Nov 04, 2019 12:08 am

Re: Ac not as cold when car warms up

Postby Miggy » Sat Nov 23, 2019 4:11 pm

Dougflas wrote:Clamp off the heater.


I'd like to but then i wouldnt have a way to control the temp when its cold outside. Its very humid here so it isnt comfortable using the car with ac off, specially when its raining.
Miggy
Posts: 23
Joined: Mon Nov 04, 2019 12:08 am

Re: Ac not as cold when car warms up

Postby Miggy » Sat Nov 23, 2019 4:15 pm

Cusser wrote:
Miggy wrote:Hey guys, i have a new problem with my car ac that just showed up recently. The ac performance decreases as the car warms up.

These are the readings with the gauges i bought:
All of the readings at idle speed, max fan speed and in my garage.


I'd like to see both low and high pressures at about 1800 rpm. Idle is not where to test.



Alright, ill get the readings at 1800 rpm. Its quite cold here right now so ill take it when it gets hotter later in the day.
Miggy
Posts: 23
Joined: Mon Nov 04, 2019 12:08 am

Re: Ac not as cold when car warms up

Postby Miggy » Sat Nov 23, 2019 4:18 pm

I forgot to mention that the problem appeared a few days after i had my evaporator replaced with a "new used" one. I brought it back to the shop but the ac guy without a thermometer told me the pressures are fine its cold.

The problem also progressively gets worse the longer you run the car. I got stuck in stand still traffic for nearly 30 mins and the cooling was basically non existent.

Edit: And it got cold again when the traffic started moving.
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Cusser
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Re: Ac not as cold when car warms up

Postby Cusser » Sat Nov 23, 2019 4:36 pm

Miggy wrote:The problem also progressively gets worse the longer you run the car. I got stuck in stand still traffic for nearly 30 mins and the cooling was basically non existent.

Edit: And it got cold again when the traffic started moving.


This seems to indicate a bad fan clutch to me. If your vehicle (you didn't state year, brand, model) has electric radiator/condenser fans, then NEVER MIND!!


Miggy wrote:I forgot to mention that the problem appeared a few days after i had my evaporator replaced with a "new used" one. I brought it back to the shop but the ac guy without a thermometer told me the pressures are fine its cold.


If such evaporator is not exactly the same as the original one, may affect the oz. refrigerant required.
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Tim
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Re: Ac not as cold when car warms up

Postby Tim » Sat Nov 23, 2019 4:55 pm

Was the replacement evap surrounded by insulation. sometimes aftermarket cores let air pass by the sides of the core.
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Miggy
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Re: Ac not as cold when car warms up

Postby Miggy » Tue Nov 26, 2019 2:30 am

Cusser wrote:
Miggy wrote:The problem also progressively gets worse the longer you run the car. I got stuck in stand still traffic for nearly 30 mins and the cooling was basically non existent.

Edit: And it got cold again when the traffic started moving.


This seems to indicate a bad fan clutch to me. If your vehicle (you didn't state year, brand, model) has electric radiator/condenser fans, then NEVER MIND!!


Miggy wrote:I forgot to mention that the problem appeared a few days after i had my evaporator replaced with a "new used" one. I brought it back to the shop but the ac guy without a thermometer told me the pressures are fine its cold.


If such evaporator is not exactly the same as the original one, may affect the oz. refrigerant required.


I have electric fans.

The used evaporator is an original nissan one.
Miggy
Posts: 23
Joined: Mon Nov 04, 2019 12:08 am

Re: Ac not as cold when car warms up

Postby Miggy » Tue Nov 26, 2019 2:31 am

Tim wrote:Was the replacement evap surrounded by insulation. sometimes aftermarket cores let air pass by the sides of the core.


Yes, this evaporator has insulation. Funny though that the original evaporator that came with the car didnt have any insulation wrapped around it.

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