The invention relates to a refrigerant circuit for thermally conditioning a vehicle passenger compartment, comprising a plurality of branches containing at least one exchanger, of which branch a first branch is in series with a second branch and a third branch, said second branch being in parallel with said third branch, and a means of placing the third branch m communication with the second branch, said means being installed between a sector of the third branch which sector is situated downstream of an external exchanger and a portion of the second branch which is situated upstream of a first control member.
