vacuum gauge low reading running on aircond

[upontheriversky]

hi,

at idle the vacuum gauge stays at 21 mmhg but when aircond is switched on, it dropped to somewhere around 16 mmhg

is this normal? if it is, can someone explain how running on aircond at idle decreases pressure drop inside plenum?

 

[sgwangacc]

hi,

at idle the vacuum gauge stays at 21 mmhg but when aircond is switched on, it dropped to somewhere around 16 mmhg

is this normal? if it is, can someone explain how running on aircond at idle decreases pressure drop inside plenum?

Hi upon,

Think you mean low pressure indicators, don't you?
Manifold gauge is widely used in these days, if compared to vacuum gauge.

If you usually drive the car, the low pressure will be around 80-90mmhg. When the air cond is switched on, the low pressure will dropped to around 30-50mmHg.

Hope this helps. :)

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Syarikat Aksesori Kereta Sungai Wang has long established in 1982 and located at Jalan Ipoh, Kuala Lumpur. We are experienced in car accessories, car audio system and car alarm system installation, car windows tinting and also air conditioner service. We ensure our qualified employees are skillful to cater to every automobile and fulfill all customer needs.

 

[upontheriversky]

im not sure how to relate to your terms coz im a noob so enlighten me :D i have installed a vacuum gauge in my car where the vacuum hose connects to the plenum.

at idle, i get 21mmhg steady, and acceleration wil give a jump to 5mmhg close to 0 atmosphere pressure which is normal

but when compressor kicks in, it jumps from 21mmhg to 16mmhg and went back to 21mmhg after compressor stops

so im trying to figure whether the compressor takes in air from the manifold for our aircond?

 

[me2kimi]

Ithink it is normal condition. When u turn on aircon, aircon bypass valve will alow more air to enter into manifold. This will result idling speed become higher but vacuum will ber lower.

 

[upontheriversky]

thats the explanation ive been waiting for. thanks!

 

[sgwangacc]

i see... thought the gauge you mentioned is used by the technicians/mechanics :willy:

 

[infinity.melvin]

something useful for vacuum readings

 

[upontheriversky]

my case is not included in all the readings above